Display system with spatial light modulator illumination for divided pupils

ABSTRACT

Illuminations systems that separate different colors into laterally displaced beams may be used to direct different color image content into an eyepiece for displaying images in the eye. Such an eyepiece may be used, for example, for an augmented reality head mounted display. Illumination systems may be provided that utilize one or more waveguides to direct light from a light source towards a spatial light modulator. Light from the spatial light modulator may be directed towards an eyepiece. Some aspects of the invention provide for light of different colors to be outcoupled at different angles from the one or more waveguides and directed along different beam paths.

INCORPORATION BY REFERENCE

This application claims the benefit of priority under 35 U.S.C. § 119(e)to U.S. Provisional Application No. 62/474,568 (Attorney Docket No.MLEAP.084PR), filed on Mar. 21, 2017, which is hereby incorporated byreference herein in its entirety.

BACKGROUND Field

The present disclosure relates to optical devices, including virtualreality and augmented reality imaging and visualization systems.

Description of the Related Art

Modern computing and display technologies have facilitated thedevelopment of systems for so called “virtual reality” or “augmentedreality” experiences, wherein digitally reproduced images or portionsthereof are presented to a user in a manner wherein they seem to be, ormay be perceived as, real. A virtual reality, or “VR”, scenariotypically involves presentation of digital or virtual image informationwithout transparency to other actual real-world visual input; anaugmented reality, or “AR”, scenario typically involves presentation ofdigital or virtual image information as an augmentation to visualizationof the actual world around the user. A mixed reality, or “MR”, scenariois a type of AR scenario and typically involves virtual objects that areintegrated into, and responsive to, the natural world. For example, inan MR scenario, AR image content may be blocked by or otherwise beperceived as interacting with objects in the real world.

Referring to FIG. 1, an augmented reality scene 10 is depicted wherein auser of an AR technology sees a real-world park-like setting 20featuring people, trees, buildings in the background, and a concreteplatform 30. In addition to these items, the user of the AR technologyalso perceives that he “sees” “virtual content” such as a robot statue40 standing upon the real-world platform 30, and a cartoon-like avatarcharacter 50 flying by which seems to be a personification of a bumblebee, even though these elements 40, 50 do not exist in the real world.Because the human visual perception system is complex, it is challengingto produce an AR technology that facilitates a comfortable,natural-feeling, rich presentation of virtual image elements amongstother virtual or real-world imagery elements.

Systems and methods disclosed herein address various challenges relatedto AR and VR technology.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a user's view of augmented reality (AR) through an ARdevice.

FIG. 2 illustrates an example of a wearable display system.

FIG. 3 illustrates a conventional display system for simulatingthree-dimensional imagery for a user.

FIG. 4 illustrates aspects of an approach for simulatingthree-dimensional imagery using multiple depth planes.

FIGS. 5A-5C illustrate relationships between radius of curvature andfocal radius.

FIG. 6 illustrates an example of a waveguide stack for outputting imageinformation to a user.

FIG. 7 illustrates an example of exit beams outputted by a waveguide.

FIG. 8 illustrates an example of a stacked waveguide assembly in whicheach depth plane includes images formed using multiple differentcomponent colors.

FIG. 9A illustrates a cross-sectional side view of an example of a setof stacked waveguides that each includes an incoupling optical element.

FIG. 9B illustrates a perspective view of an example of the plurality ofstacked waveguides of FIG. 9A.

FIG. 9C illustrates a top-down plan view of an example of the pluralityof stacked waveguides of FIGS. 9A and 9B.

FIG. 9D illustrate a waveguide-based image source that provides multipleinput beams to a plurality incoupling optical elements integrated with astack of waveguides that form part of an eyepiece.

FIGS. 10A and 10B illustrate a waveguide-based image source comprising asingle waveguide that may receive white light and includes anoutcoupling optical element that has dispersion and that directsdifferent color light (e.g., red, green, blue) into differentdirections.

FIGS. 11A-11C illustrate a waveguide-based image source comprising aplurality of waveguides each optically coupled to a different color LED(e.g., red, green, blue) having outcoupling optical elements that directthe light in the respective waveguides into different directions.

FIG. 11D shows a waveguide-based image source comprising three colorlight emitters and two waveguides where two of the colors from twoemitters are combined into a single waveguide.

FIG. 12A illustrates a waveguide-based image source comprising a singlewaveguide that may be coupled to a white LED and outcouples the light toa plurality of shutters with corresponding color filters to selectivelypass different colors of light at different times.

FIG. 12B is a flow chart that illustrates an example refresh process fora waveguide-based image source as shown in FIG. 12A comprising anshutter and a spatial light modulator.

FIG. 13 illustrates a waveguide-based image source comprising singlewaveguide that may be coupled to a white LED and that outcouples thelight to a plural of dichroic beamsplitters that split the differentcolor and produces different color beams that are at different lateralpositions.

FIGS. 14A and 14B illustrates a waveguide-based image source comprisinga waveguide illuminated by a point light source and a line light source,respectively.

FIG. 14C-14E illustrate additional arrangements for coupling light intoa waveguide.

FIG. 15A illustrates a waveguide-based image source comprising awaveguide and an outcoupling optical element comprising volume phasediffractive element.

FIG. 15B illustrates waveguide-based light distribution devicecomprising a stack of volume phase grating (VPG) diffractive elementsfor different colors.

FIG. 15C illustrates waveguide-based light distribution devicecomprising a stack of volume phase grating (VPG) diffractive elementsfor different angles.

FIG. 16 illustrates a waveguide-based image source comprising awaveguide and an outcoupling optical element comprising a cholestericliquid crystal grating (CLCG).

FIGS. 17A and 17B illustrate a waveguide-based light distribution devicethat may be configured to utilize off-axis illumination.

FIG. 18 illustrates a waveguide-based image source comprising awedge-shaped waveguide.

SUMMARY OF THE INVENTION

According to some aspects, a display device may be provided, comprising:

one or more light emitters configured to emit light;

a first waveguide disposed with respect to said one or more lightemitters to receive light from said one or more light emitters, saidfirst waveguide configured to (i) eject light out of said waveguidehaving a first color along a first path, and (ii) eject light out ofsaid first waveguide having a second color along a second path; and

a spatial light modulator disposed with respect to said first waveguideto receive said light ejected from said waveguide and modulate saidlight,

wherein said one or more light emitters is configured to emit lighthaving a spectral distribution that includes spectral componentscorresponding to said first and second colors, and

wherein said display device is configured such that said light from saidfirst waveguide of said first color and said second color after beingmodulated by said spatial light modulator is directed along saidrespective first and second paths at different angles and is incident onrespective first and second spatial locations a distance from said firstwaveguide and spatial light modulator.

According to other aspects, a display device may be provided,comprising:

one or more light emitters configured to emit light;

a first waveguide disposed with respect to said one or more lightemitters to receive light from said one or more light emitters such thatsaid light is guided therein by total internal reflection, said firstwaveguide configured to eject light guided within said first waveguideout of said waveguide;

a shutter system comprising a first shutter and a second shutter andcorresponding first and second color filters configured to selectivelytransmit first and second color light, respectively, said shutter systemdisposed with respect to said first waveguide to receive said lightejected from said waveguide such that light of said first and secondcolors from said first waveguide passes through said respective firstand second color filters, respectively, as well as through saidrespective first shutter and second shutters along respective first andsecond optical paths to respective first and second spatial location ata distance from said first waveguide;

a spatial light modulator disposed with respect to said first waveguideto receive said light ejected from said waveguide and modulate saidlight, said shutter system disposed with respect to said spatial lightmodulator such that said modulated light is directed along said firstand second optical paths to said respective first and second spatiallocation at a distance from said spatial light modulator; and

electronics in communication with said shutter system and said spatiallight modulator to (i) open said shutter associated with said firstcolor at a first time and close said shutter associated with said secondcolor when said spatial light modulator is configured to present animage corresponding to said first color and (ii) to open said shutterassociated with said second color and close said shutter associated withsaid first color at a second time when said spatial light modulator isconfigured to present an image corresponding to said second color,

wherein said one or more light emitters is configured to emit lighthaving a spectral distribution that includes spectral componentscorresponding to said first and second colors. According to otherembodiments, a display device may be provided, comprising:

one or more light emitters configured to emit light;

a first waveguide disposed with respect to said one or more lightemitters to receive light from said one or more light emitters such thatsaid light is guided therein by total internal reflection, said firstwaveguide configured to eject light guided within said first waveguideout of said waveguide;

a first beamsplitter configured to selectively direct light of a firstspectral distribution and a first color light along a first directionand a second spectral distribution along a second direction, said firstbeamsplitter disposed with respect to said first waveguide to receivesaid light ejected from said waveguide such that light of said first andsecond spectral distributions from said first waveguide are incident onsaid first beamsplitter and said light having said first and secondspectral distributions are directed along respective first and secondoptical paths, said light of said first spectral distribution and firstcolor being directed to a respective first spatial location at adistance from said first waveguide; and

a spatial light modulator disposed with respect to said first waveguideto receive said light ejected from said waveguide and modulate saidlight, said first beamsplitter disposed with respect to said spatiallight modulator such that said modulated light is directed along saidfirst and second optical paths and said light of said first color isdirected to said first spatial location at a distance from said spatiallight modulator,

wherein said one or more light emitters is configured to emit lighthaving a spectral distribution that includes spectral componentscorresponding to said first and second spectral distribution directedalong said respective first and second optical paths.

According to further aspects, a display device may be provided for ahead mounted display comprising:

-   -   a waveguide based image source comprising:        -   one or more light emitters configured to emit light;        -   one or more waveguides disposed with respect to said one or            more light emitters to receive light from said one or more            light emitters such that light is guided within said one or            more light guides via total internal reflection, said one or            more waveguides configured to eject light out of said            waveguides; and        -   a spatial light modulator disposed with respect to one or            more waveguides to receive said light ejected from said one            or more waveguides and modulate said light,    -   wherein said one or more light emitters are configured to emit        light having a spectral distribution that includes spectral        components corresponding to first and second colors, and    -   said waveguide based image source is configured such that said        light of said first and second colors after being modulated by        said spatial light modulator is directed along said respective        first and second paths and is incident on respective first and        second spatial locations a distance from said one or more        waveguides and said spatial light modulator, and    -   an eyepiece element comprising a waveguide based light        distribution system comprising:        -   a first waveguide having associated therewith an in-coupling            optical element disposed with respect to one or more first            waveguides and said first path to receive light from said            one or more waveguides after being modulated by said spatial            light modulator; and        -   a second waveguide having associated therewith an            in-coupling optical element disposed with respect to said            one or more waveguides and said second path to receive light            from said one or more waveguides after being modulated by            said spatial light modulator,    -   wherein said in-coming optical elements associated with said        first and second waveguides, respectively, are located at said        first and second spatial locations along said first and second        paths respectively to receive said light of said first and        second colors, respectively.

DETAILED DESCRIPTION

Reference will now be made to the figures, in which like referencenumerals refer to like parts throughout. It will be appreciated thatembodiments disclosed herein include optical systems, including displaysystems, generally. In some embodiments, the display systems arewearable, which may advantageously provide a more immersive VR or ARexperience. For example, displays containing one or more waveguides(e.g., a stack of waveguides) may be configured to be worn positioned infront of the eyes of a user, or viewer. In some embodiments, two stacksof waveguides, one for each eye of a viewer, may be utilized to providedifferent images to each eye.

Example Display Systems

FIG. 2 illustrates an example of wearable display system 60. The displaysystem 60 includes a display 70, and various mechanical and electronicmodules and systems to support the functioning of that display 70. Thedisplay 70 may be coupled to a frame 80, which is wearable by a displaysystem user or viewer 90 and which is configured to position the display70 in front of the eyes of the user 90. The display 70 may be consideredeyewear in some embodiments. In some embodiments, a speaker 100 iscoupled to the frame 80 and configured to be positioned adjacent the earcanal of the user 90 (in some embodiments, another speaker, not shown,is positioned adjacent the other ear canal of the user to providestereo/shapeable sound control). In some embodiments, the display systemmay also include one or more microphones 110 or other devices to detectsound. In some embodiments, the microphone is configured to allow theuser to provide inputs or commands to the system 60 (e.g., the selectionof voice menu commands, natural language questions, etc.), and/or mayallow audio communication with other persons (e.g., with other users ofsimilar display systems. The microphone may further be configured as aperipheral sensor to collect audio data (e.g., sounds from the userand/or environment). In some embodiments, the display system may alsoinclude a peripheral sensor 120 a, which may be separate from the frame80 and attached to the body of the user 90 (e.g., on the head, torso, anextremity, etc. of the user 90). The peripheral sensor 120 a may beconfigured to acquire data characterizing the physiological state of theuser 90 in some embodiments. For example, the sensor 120 a may be anelectrode.

With continued reference to FIG. 2, the display 70 is operativelycoupled by communications link 130, such as by a wired lead or wirelessconnectivity, to a local data processing module 140 which may be mountedin a variety of configurations, such as fixedly attached to the frame80, fixedly attached to a helmet or hat worn by the user, embedded inheadphones, or otherwise removably attached to the user 90 (e.g., in abackpack-style configuration, in a belt-coupling style configuration).Similarly, the sensor 120 a may be operatively coupled by communicationslink 120 b, e.g., a wired lead or wireless connectivity, to the localprocessor and data module 140. The local processing and data module 140may comprise a hardware processor, as well as digital memory, such asnon-volatile memory (e.g., flash memory or hard disk drives), both ofwhich may be utilized to assist in the processing, caching, and storageof data. The data include data a) captured from sensors (which may be,e.g., operatively coupled to the frame 80 or otherwise attached to theuser 90), such as image capture devices (such as cameras), microphones,inertial measurement units, accelerometers, compasses, GPS units, radiodevices, gyros, and/or other sensors disclosed herein; and/or b)acquired and/or processed using remote processing module 150 and/orremote data repository 160 (including data relating to virtual content),possibly for passage to the display 70 after such processing orretrieval. The local processing and data module 140 may be operativelycoupled by communication links 170, 180, such as via a wired or wirelesscommunication links, to the remote processing module 150 and remote datarepository 160 such that these remote modules 150, 160 are operativelycoupled to each other and available as resources to the local processingand data module 140. In some embodiments, the local processing and datamodule 140 may include one or more of the image capture devices,microphones, inertial measurement units, accelerometers, compasses, GPSunits, radio devices, and/or gyros. In some other embodiments, one ormore of these sensors may be attached to the frame 80, or may bestandalone structures that communicate with the local processing anddata module 140 by wired or wireless communication pathways.

With continued reference to FIG. 2, in some embodiments, the remoteprocessing module 150 may comprise one or more processors configured toanalyze and process data and/or image information. In some embodiments,the remote data repository 160 may comprise a digital data storagefacility, which may be available through the internet or othernetworking configuration in a “cloud” resource configuration. In someembodiments, the remote data repository 160 may include one or moreremote servers, which provide information, e.g., information forgenerating augmented reality content, to the local processing and datamodule 140 and/or the remote processing module 150. In some embodiments,all data is stored and all computations are performed in the localprocessing and data module, allowing fully autonomous use from a remotemodule.

The perception of an image as being “three-dimensional” or “3-D” may beachieved by providing slightly different presentations of the image toeach eye of the viewer. FIG. 3 illustrates a conventional display systemfor simulating three-dimensional imagery for a user. Two distinct images190, 200—one for each eye 210, 220—are outputted to the user. The images190, 200 are spaced from the eyes 210, 220 by a distance 230 along anoptical or z-axis that is parallel to the line of sight of the viewer.The images 190, 200 are flat and the eyes 210, 220 may focus on theimages by assuming a single accommodated state. Such 3-D display systemsrely on the human visual system to combine the images 190, 200 toprovide a perception of depth and/or scale for the combined image.

It will be appreciated, however, that the human visual system is morecomplicated and providing a realistic perception of depth is morechallenging. For example, many viewers of conventional “3-D” displaysystems find such systems to be uncomfortable or may not perceive asense of depth at all. Without being limited by theory, it is believedthat viewers of an object may perceive the object as being“three-dimensional” due to a combination of vergence and accommodation.Vergence movements (i.e., rotation of the eyes so that the pupils movetoward or away from each other to converge the lines of sight of theeyes to fixate upon an object) of the two eyes relative to each otherare closely associated with focusing (or “accommodation”) of the lensesand pupils of the eyes. Under normal conditions, changing the focus ofthe lenses of the eyes, or accommodating the eyes, to change focus fromone object to another object at a different distance will automaticallycause a matching change in vergence to the same distance, under arelationship known as the “accommodation-vergence reflex,” as well aspupil dilation or constriction. Likewise, a change in vergence willtrigger a matching change in accommodation of lens shape and pupil size,under normal conditions. As noted herein, many stereoscopic or “3-D”display systems display a scene using slightly different presentations(and, so, slightly different images) to each eye such that athree-dimensional perspective is perceived by the human visual system.Such systems are uncomfortable for many viewers, however, since they,among other things, simply provide a different presentation of a scene,but with the eyes viewing all the image information at a singleaccommodated state, and work against the “accommodation-vergencereflex.” Display systems that provide a better match betweenaccommodation and vergence may form more realistic and comfortablesimulations of three-dimensional imagery contributing to increasedduration of wear and in turn compliance to diagnostic and therapyprotocols.

FIG. 4 illustrates aspects of an approach for simulatingthree-dimensional imagery using multiple depth planes. With reference toFIG. 4, objects at various distances from eyes 210, 220 on the z-axisare accommodated by the eyes 210, 220 so that those objects are infocus. The eyes 210, 220 assume particular accommodated states to bringinto focus objects at different distances along the z-axis.Consequently, a particular accommodated state may be said to beassociated with a particular one of depth planes 240, with has anassociated focal distance, such that objects or parts of objects in aparticular depth plane are in focus when the eye is in the accommodatedstate for that depth plane. In some embodiments, three-dimensionalimagery may be simulated by providing different presentations of animage for each of the eyes 210, 220, and also by providing differentpresentations of the image corresponding to each of the depth planes.While shown as being separate for clarity of illustration, it will beappreciated that the fields of view of the eyes 210, 220 may overlap,for example, as distance along the z-axis increases. In addition, whileshown as flat for ease of illustration, it will be appreciated that thecontours of a depth plane may be curved in physical space, such that allfeatures in a depth plane are in focus with the eye in a particularaccommodated state.

The distance between an object and the eye 210 or 220 may also changethe amount of divergence of light from that object, as viewed by thateye. FIGS. 5A-5C illustrate relationships between distance and thedivergence of light rays. The distance between the object and the eye210 is represented by, in order of decreasing distance, R1, R2, and R3.As shown in FIGS. 5A-5C, the light rays become more divergent asdistance to the object decreases. As distance increases, the light raysbecome more collimated. Stated another way, it may be said that thelight field produced by a point (the object or a part of the object) hasa spherical wavefront curvature, which is a function of how far away thepoint is from the eye of the user. The curvature increases withdecreasing distance between the object and the eye 210. Consequently, atdifferent depth planes, the degree of divergence of light rays is alsodifferent, with the degree of divergence increasing with decreasingdistance between depth planes and the viewer's eye 210. While only asingle eye 210 is illustrated for clarity of illustration in FIGS. 5A-5Cand other figures herein, it will be appreciated that the discussionsregarding eye 210 may be applied to both eyes 210 and 220 of a viewer.

Without being limited by theory, it is believed that the human eyetypically can interpret a finite number of depth planes to provide depthperception. Consequently, a highly believable simulation of perceiveddepth may be achieved by providing, to the eye, different presentationsof an image corresponding to each of these limited number of depthplanes. The different presentations may be separately focused by theviewer's eyes, thereby helping to provide the user with depth cues basedon the accommodation of the eye required to bring into focus differentimage features for the scene located on different depth plane and/orbased on observing different image features on different depth planesbeing out of focus.

FIG. 6 illustrates an example of a waveguide stack for outputting imageinformation to a user. A display system 250 includes a stack ofwaveguides, or stacked waveguide assembly, 260 that may be utilized toprovide three-dimensional perception to the eye/brain using a pluralityof waveguides 270, 280, 290, 300, 310. In some embodiments, the displaysystem 250 is the system 60 of FIG. 2, with FIG. 6 schematically showingsome parts of that system 60 in greater detail. For example, thewaveguide assembly 260 may be part of the display 70 of FIG. 2. It willbe appreciated that the display system 250 may be considered a lightfield display in some embodiments.

With continued reference to FIG. 6, the waveguide assembly 260 may alsoinclude a plurality of features 320, 330, 340, 350 between thewaveguides. In some embodiments, the features 320, 330, 340, 350 may beone or more lenses. The waveguides 270, 280, 290, 300, 310 and/or theplurality of lenses 320, 330, 340, 350 may be configured to send imageinformation to the eye with various levels of wavefront curvature orlight ray divergence. Each waveguide level may be associated with aparticular depth plane and may be configured to output image informationcorresponding to that depth plane. Image injection devices 360, 370,380, 390, 400 may function as a source of light for the waveguides andmay be utilized to inject image information into the waveguides 270,280, 290, 300, 310, each of which may be configured, as describedherein, to distribute incoming light across each respective waveguide,for output toward the eye 210. Light exits an output surface 410, 420,430, 440, 450 of the image injection devices 360, 370, 380, 390, 400 andis injected into a corresponding input surface 460, 470, 480, 490, 500of the waveguides 270, 280, 290, 300, 310. In some embodiments, the eachof the input surfaces 460, 470, 480, 490, 500 may be an edge of acorresponding waveguide, or may be part of a major surface of thecorresponding waveguide (that is, one of the waveguide surfaces directlyfacing the world 510 or the viewer's eye 210). In some embodiments, asingle beam of light (e.g. a collimated beam) may be injected into eachwaveguide to output an entire field of cloned collimated beams that aredirected toward the eye 210 at particular angles (and amounts ofdivergence) corresponding to the depth plane associated with aparticular waveguide. In some embodiments, a single one of the imageinjection devices 360, 370, 380, 390, 400 may be associated with andinject light into a plurality (e.g., three) of the waveguides 270, 280,290, 300, 310.

In some embodiments, the image injection devices 360, 370, 380, 390, 400are discrete displays that each produce image information for injectioninto a corresponding waveguide 270, 280, 290, 300, 310, respectively. Insome other embodiments, the image injection devices 360, 370, 380, 390,400 are the output ends of a single multiplexed display which may, e.g.,pipe image information via one or more optical conduits (such as fiberoptic cables) to each of the image injection devices 360, 370, 380, 390,400. It will be appreciated that the image information provided by theimage injection devices 360, 370, 380, 390, 400 may include light ofdifferent wavelengths, or colors (e.g., different component colors, asdiscussed herein).

In some embodiments, the light injected into the waveguides 270, 280,290, 300, 310 is provided by a light projector system 520, whichcomprises a light module 530, which may include a light emitter, such asa light emitting diode (LED). The light from the light module 530 may bedirected to and modified by a light modulator 540, e.g., a spatial lightmodulator, via a beam splitter 550. The light modulator 540 may beconfigured to change the perceived intensity of the light injected intothe waveguides 270, 280, 290, 300, 310. Examples of spatial lightmodulators include liquid crystal displays (LCD) including a liquidcrystal on silicon (LCOS) displays.

In some embodiments, the display system 250 may be a scanning fiberdisplay comprising one or more scanning fibers configured to projectlight in various patterns (e.g., raster scan, spiral scan, Lissajouspatterns, etc.) into one or more waveguides 270, 280, 290, 300, 310 andultimately to the eye 210 of the viewer. In some embodiments, theillustrated image injection devices 360, 370, 380, 390, 400 mayschematically represent a single scanning fiber or a bundle of scanningfibers configured to inject light into one or a plurality of thewaveguides 270, 280, 290, 300, 310. In some other embodiments, theillustrated image injection devices 360, 370, 380, 390, 400 mayschematically represent a plurality of scanning fibers or a plurality ofbundles of scanning fibers, each of which are configured to inject lightinto an associated one of the waveguides 270, 280, 290, 300, 310. Itwill be appreciated that one or more optical fibers may be configured totransmit light from the light module 530 to the one or more waveguides270, 280, 290, 300, 310. It will be appreciated that one or moreintervening optical structures may be provided between the scanningfiber, or fibers, and the one or more waveguides 270, 280, 290, 300, 310to, e.g., redirect light exiting the scanning fiber into the one or morewaveguides 270, 280, 290, 300, 310.

A controller 560 controls the operation of one or more of the stackedwaveguide assembly 260, including operation of the image injectiondevices 360, 370, 380, 390, 400, the light emitter 530, and the lightmodulator 540. In some embodiments, the controller 560 is part of thelocal data processing module 140. The controller 560 includesprogramming (e.g., instructions in a non-transitory medium) thatregulates the timing and provision of image information to thewaveguides 270, 280, 290, 300, 310 according to, e.g., any of thevarious schemes disclosed herein. In some embodiments, the controllermay be a single integral device, or a distributed system connected bywired or wireless communication channels. The controller 560 may be partof the processing modules 140 or 150 (FIG. 2) in some embodiments.

With continued reference to FIG. 6, the waveguides 270, 280, 290, 300,310 may be configured to propagate light within each respectivewaveguide by total internal reflection (TIR). The waveguides 270, 280,290, 300, 310 may each be planar or have another shape (e.g., curved),with major top and bottom surfaces and edges extending between thosemajor top and bottom surfaces. In the illustrated configuration, thewaveguides 270, 280, 290, 300, 310 may each include out-coupling opticalelements 570, 580, 590, 600, 610 that are configured to extract lightout of a waveguide by redirecting the light, propagating within eachrespective waveguide, out of the waveguide to output image informationto the eye 210. Extracted light may also be referred to as out-coupledlight and the out-coupling optical elements light may also be referredto light extracting optical elements. An extracted beam of light may beoutputted by the waveguide at locations at which the light propagatingin the waveguide strikes a light extracting optical element. Theout-coupling optical elements 570, 580, 590, 600, 610 may, for example,be gratings, including diffractive optical features, as discussedfurther herein. While illustrated disposed at the bottom major surfacesof the waveguides 270, 280, 290, 300, 310, for ease of description anddrawing clarity, in some embodiments, the out-coupling optical elements570, 580, 590, 600, 610 may be disposed at the top and/or bottom majorsurfaces, and/or may be disposed directly in the volume of thewaveguides 270, 280, 290, 300, 310, as discussed further herein. In someembodiments, the out-coupling optical elements 570, 580, 590, 600, 610may be formed in a layer of material that is attached to a transparentsubstrate to form the waveguides 270, 280, 290, 300, 310. In some otherembodiments, the waveguides 270, 280, 290, 300, 310 may be a monolithicpiece of material and the out-coupling optical elements 570, 580, 590,600, 610 may be formed on a surface and/or in the interior of that pieceof material.

With continued reference to FIG. 6, as discussed herein, each waveguide270, 280, 290, 300, 310 is configured to output light to form an imagecorresponding to a particular depth plane. For example, the waveguide270 nearest the eye may be configured to deliver collimated light (whichwas injected into such waveguide 270), to the eye 210. The collimatedlight may be representative of the optical infinity focal plane. Thenext waveguide up 280 may be configured to send out collimated lightwhich passes through the first lens 350 (e.g., a negative lens) beforeit can reach the eye 210; such first lens 350 may be configured tocreate a slight convex wavefront curvature so that the eye/braininterprets light coming from that next waveguide up 280 as coming from afirst focal plane closer inward toward the eye 210 from opticalinfinity. Similarly, the third up waveguide 290 passes its output lightthrough both the first 350 and second 340 lenses before reaching the eye210; the combined optical power of the first 350 and second 340 lensesmay be configured to create another incremental amount of wavefrontcurvature so that the eye/brain interprets light coming from the thirdwaveguide 290 as coming from a second focal plane that is even closerinward toward the person from optical infinity than was light from thenext waveguide up 280.

The other waveguide layers 300, 310 and lenses 330, 320 are similarlyconfigured, with the highest waveguide 310 in the stack sending itsoutput through all of the lenses between it and the eye for an aggregatefocal power representative of the closest focal plane to the person. Tocompensate for the stack of lenses 320, 330, 340, 350 whenviewing/interpreting light coming from the world 510 on the other sideof the stacked waveguide assembly 260, a compensating lens layer 620 maybe disposed at the top of the stack to compensate for the aggregatepower of the lens stack 320, 330, 340, 350 below. Such a configurationprovides as many perceived focal planes as there are availablewaveguide/lens pairings. Both the out-coupling optical elements of thewaveguides and the focusing aspects of the lenses may be static (i.e.,not dynamic or electro-active). In some alternative embodiments, eitheror both may be dynamic using electro-active features.

In some embodiments, two or more of the waveguides 270, 280, 290, 300,310 may have the same associated depth plane. For example, multiplewaveguides 270, 280, 290, 300, 310 may be configured to output imagesset to the same depth plane, or multiple subsets of the waveguides 270,280, 290, 300, 310 may be configured to output images set to the sameplurality of depth planes, with one set for each depth plane. This canprovide advantages for forming a tiled image to provide an expandedfield of view at those depth planes.

With continued reference to FIG. 6, the out-coupling optical elements570, 580, 590, 600, 610 may be configured to both redirect light out oftheir respective waveguides and to output this light with theappropriate amount of divergence or collimation for a particular depthplane associated with the waveguide. As a result, waveguides havingdifferent associated depth planes may have different configurations ofout-coupling optical elements 570, 580, 590, 600, 610, which outputlight with a different amount of divergence depending on the associateddepth plane. In some embodiments, the light extracting optical elements570, 580, 590, 600, 610 may be volumetric or surface features, which maybe configured to output light at specific angles. For example, the lightextracting optical elements 570, 580, 590, 600, 610 may be volumeholograms, surface holograms, and/or diffraction gratings. In someembodiments, the features 320, 330, 340, 350 may not be lenses; rather,they may simply be spacers (e.g., cladding layers and/or structures forforming air gaps).

In some embodiments, the out-coupling optical elements 570, 580, 590,600, 610 are diffractive features that form a diffraction pattern, or“diffractive optical element” (also referred to herein as a “DOE”).Preferably, the DOE's have a sufficiently low diffraction efficiency sothat only a portion of the light of the beam is deflected away towardthe eye 210 with each intersection of the DOE, while the rest continuesto move through a waveguide via TIR. The light carrying the imageinformation is thus divided into a number of related exit beams thatexit the waveguide at a multiplicity of locations and the result is afairly uniform pattern of exit emission toward the eye 210 for thisparticular collimated beam bouncing around within a waveguide.

In some embodiments, one or more DOEs may be switchable between “on”states in which they actively diffract, and “off” states in which theydo not significantly diffract. For instance, a switchable DOE maycomprise a layer of polymer dispersed liquid crystal, in whichmicrodroplets comprise a diffraction pattern in a host medium, and therefractive index of the microdroplets may be switched to substantiallymatch the refractive index of the host material (in which case thepattern does not appreciably diffract incident light) or themicrodroplet may be switched to an index that does not match that of thehost medium (in which case the pattern actively diffracts incidentlight).

In some embodiments, a camera assembly 630 (e.g., a digital camera,including visible light and infrared light cameras) may be provided tocapture images of the eye 210 and/or tissue around the eye 210 to, e.g.,detect user inputs and/or to monitor the physiological state of theuser. As used herein, a camera may be any image capture device. In someembodiments, the camera assembly 630 may include an image capture deviceand a light emitter to project light (e.g., infrared light) to the eye,which may then be reflected by the eye and detected by the image capturedevice. In some embodiments, the camera assembly 630 may be attached tothe frame 80 (FIG. 2) and may be in electrical communication with theprocessing modules 140 and/or 150, which may process image informationfrom the camera assembly 630 to make various determinations regarding,e.g., the physiological state of the user, as discussed herein. It willbe appreciated that information regarding the physiological state ofuser may be used to determine the behavioral or emotional state of theuser. Examples of such information include movements of the user and/orfacial expressions of the user. The behavioral or emotional state of theuser may then be triangulated with collected environmental and/orvirtual content data so as to determine relationships between thebehavioral or emotional state, physiological state, and environmental orvirtual content data. In some embodiments, one camera assembly 630 maybe utilized for each eye, to separately monitor each eye.

With reference now to FIG. 7, an example of exit beams outputted by awaveguide is shown. One waveguide is illustrated, but it will beappreciated that other waveguides in the waveguide assembly 260 (FIG. 6)may function similarly, where the waveguide assembly 260 includesmultiple waveguides. Light 640 is injected into the waveguide 270 at theinput surface 460 of the waveguide 270 and propagates within thewaveguide 270 by TIR. At points where the light 640 impinges on the DOE570, a portion of the light exits the waveguide as exit beams 650. Theexit beams 650 are illustrated as substantially parallel but, asdiscussed herein, they may also be redirected to propagate to the eye210 at an angle (e.g., forming divergent exit beams), depending on thedepth plane associated with the waveguide 270. It will be appreciatedthat substantially parallel exit beams may be indicative of a waveguidewithout-coupling optical elements that out-couple light to form imagesthat appear to be set on a depth plane at a large distance (e.g.,optical infinity) from the eye 210. Other waveguides or other sets ofout-coupling optical elements may output an exit beam pattern that ismore divergent, which would require the eye 210 to accommodate to acloser distance to bring it into focus on the retina and would beinterpreted by the brain as light from a distance closer to the eye 210than optical infinity.

In some embodiments, a full color image may be formed at each depthplane by overlaying images in each of the component colors, e.g., threeor more component colors. FIG. 8 illustrates an example of a stackedwaveguide assembly in which each depth plane includes images formedusing multiple different component colors. The illustrated embodimentshows depth planes 240 a-240 f, although more or fewer depths are alsocontemplated. Each depth plane may have three or more component colorimages associated with it, including: a first image of a first color, G;a second image of a second color, R; and a third image of a third color,B. Different depth planes are indicated in the figure by differentnumbers for diopters (dpt) following the letters G, R, and B. Just asexamples, the numbers following each of these letters indicate diopters(l/m), or inverse distance of the depth plane from a viewer, and eachbox in the figures represents an individual component color image. Insome embodiments, to account for differences in the eye's focusing oflight of different wavelengths, the exact placement of the depth planesfor different component colors may vary. For example, differentcomponent color images for a given depth plane may be placed on depthplanes corresponding to different distances from the user. Such anarrangement may increase visual acuity and user comfort and/or maydecrease chromatic aberrations.

In some embodiments, light of each component color may be outputted by asingle dedicated waveguide and, consequently, each depth plane may havemultiple waveguides associated with it. In such embodiments, each box inthe figures including the letters G, R, or B may be understood torepresent an individual waveguide, and three waveguides may be providedper depth plane where three component color images are provided perdepth plane. While the waveguides associated with each depth plane areshown adjacent to one another in this drawing for ease of description,it will be appreciated that, in a physical device, the waveguides mayall be arranged in a stack with one waveguide per level. In some otherembodiments, multiple component colors may be outputted by the samewaveguide, such that, e.g., only a single waveguide may be provided perdepth plane.

With continued reference to FIG. 8, in some embodiments, G is the colorgreen, R is the color red, and B is the color blue. In some otherembodiments, other colors associated with other wavelengths of light,including magenta and cyan, may be used in addition to or may replaceone or more of red, green, or blue. In some embodiments, features 320,330, 340, and 350 may be active or passive optical filters configured toblock or selectively light from the ambient environment to the viewer'seyes.

It will be appreciated that references to a given color of lightthroughout this disclosure will be understood to encompass light of oneor more wavelengths within a range of wavelengths of light that areperceived by a viewer as being of that given color. For example, redlight may include light of one or more wavelengths in the range of about620-780 nm, green light may include light of one or more wavelengths inthe range of about 492-577 nm, and blue light may include light of oneor more wavelengths in the range of about 435-493 nm.

In some embodiments, the light emitter 530 (FIG. 6) may be configured toemit light of one or more wavelengths outside the visual perceptionrange of the viewer, for example, infrared and/or ultravioletwavelengths. In addition, the in-coupling, out-coupling, and other lightredirecting structures of the waveguides of the display 250 may beconfigured to direct and emit this light out of the display towards theuser's eye 210, e.g., for imaging and/or user stimulation applications.

With reference now to FIG. 9A, in some embodiments, light impinging on awaveguide may need to be redirected to in-couple that light into thewaveguide. An in-coupling optical element may be used to redirect andin-couple the light into its corresponding waveguide. FIG. 9Aillustrates a cross-sectional side view of an example of one or more, orset of stacked waveguides 660 that each includes an in-coupling opticalelement. The waveguides may each be configured to output light of one ormore different wavelengths, or one or more different ranges ofwavelengths. It will be appreciated that the set of stacked waveguides660 may correspond to the stack 260 (FIG. 6) and the illustratedwaveguides of the set of stacked waveguides 660 may correspond to partof the one or more waveguides 270, 280, 290, 300, 310, except that lightfrom one or more of the image injection devices 360, 370, 380, 390, 400is injected into the waveguides from a position that requires light tobe redirected for in-coupling.

The set of stacked waveguides 660 includes waveguides 670, 680, and 690.Each waveguide includes an associated in-coupling optical element (whichmay also be referred to as a light input area on the waveguide), with anin-coupling optical element 700 disposed on a major surface (e.g., anupper major surface) of the waveguide 670, an in-coupling opticalelement 710 disposed on a major surface (e.g., an upper major surface)of the waveguide 680, and an in-coupling optical element 720 disposed ona major surface (e.g., an upper major surface) of the waveguide 690. Insome embodiments, one or more of the in-coupling optical elements 700,710, 720 may be disposed on the bottom major surface of the respectivewaveguide 670, 680, 690 (particularly where the one or more in-couplingoptical elements are reflective optical elements). As illustrated, thein-coupling optical elements 700, 710, 720 may be disposed on the uppermajor surface of their respective waveguide 670, 680, 690 (or the top ofthe next lower waveguide), particularly where those in-coupling opticalelements are transmissive, deflecting optical elements. In someembodiments, the in-coupling optical elements 700, 710, 720 may bedisposed in the body of the respective waveguide 670, 680, 690. In someembodiments, as discussed herein, the in-coupling optical elements 700,710, 720 are wavelength selective, such that they selectively redirectone or more wavelengths of light, while transmitting other wavelengthsof light. While illustrated on one side or corner of their respectivewaveguide 670, 680, 690, it will be appreciated that, in someembodiments, the in-coupling optical elements 700, 710, 720 may bedisposed in other areas of their respective waveguide 670, 680, 690.

The in-coupling optical elements 700, 710, 720 may be laterally offsetfrom one another. In some embodiments, each in-coupling optical elementmay be offset such that it receives light without that light passingthrough another in-coupling optical element. For example, eachin-coupling optical element 700, 710, 720 may be configured to receivelight from a different image injection device (e.g., the image injectiondevices 360, 370, 380, 390, and 400 as shown in FIG. 6), and may beseparated (e.g., laterally spaced apart) from other in-coupling opticalelements 700, 710, 720 such that it substantially does not receive lightfrom the other ones of the in-coupling optical elements 700, 710, 720.

Each waveguide also includes associated light distributing elements withlight distributing elements 730 disposed on a major surface (e.g., a topmajor surface) of the waveguide 670, light distributing elements 740disposed on a major surface (e.g., a top major surface) of the waveguide680, and light distributing elements 750 disposed on a major surface(e.g., a top major surface) of the waveguide 690. In some otherembodiments, the light distributing elements 730, 740, 750, may bedisposed on a bottom major surface of the associated waveguides 670,680, 690, respectively. In some other embodiments, the lightdistributing elements 730, 740, 750, may be disposed on both top andbottom major surface of the associated waveguides 670, 680, 690,respectively; or the light distributing elements 730, 740, 750, may bedisposed on different ones of the top and bottom major surfaces indifferent the associated waveguides 670, 680, 690, respectively.

The waveguides 670, 680, 690 may be spaced apart and separated by gas,liquid, and/or solid layers of material. For example, as illustrated,layer 760 a may separate the waveguides 670 and 680; and layer 760 b mayseparate the waveguides 680 and 690. In some embodiments, the layers 760a and 760 b are formed of low refractive index materials (that is,materials having a lower refractive index than the material forming theimmediately adjacent one of the waveguides 670, 680, 690). Preferably,the refractive index of the material forming the layers 760 a, 760 b is0.05 or more, or 0.10 or less than the refractive index of the materialforming the waveguides 670, 680, 690. Advantageously, the lowerrefractive index layers 760 a, 760 b may function as cladding layersthat facilitate TIR of light through the waveguides 670, 680, 690 (e.g.,TIR between the top and bottom major surfaces of each waveguide). Insome embodiments, the layers 760 a, 760 b are formed of air. While notillustrated, the top and bottom of the set of stacked waveguides 660 mayinclude immediately neighboring cladding layers.

Preferably, for ease of manufacturing and other considerations, thematerial forming the waveguides 670, 680, 690 are similar or the same,and the material forming the layers 760 a, 760 b are similar or thesame. In some embodiments, the material forming the waveguides 670, 680,690 may be different between one or more waveguides, and/or the materialforming the layers 760 a, 760 b may be different, while still holding tothe various refractive index relationships noted above.

With continued reference to FIG. 9A, light rays 770, 780, 790 areincident on the set of stacked waveguides 660. The light rays 770, 780,790 may be injected into the waveguides 670, 680, 690 by one or moreimage injection devices 360, 370, 380, 390, 400.

In some embodiments, the light rays 770, 780, 790 have differentproperties, for example, different wavelengths or different ranges ofwavelengths, which may correspond to different colors. The light rays770, 780, 790 may also be laterally displaced to different locationscorresponding to the lateral locations of the in-coupling opticalelements 700, 710, 720. The in-coupling optical elements 700, 710, 720each deflect the incident light such that the light propagates through arespective one of the waveguides 670, 680, 690 by TIR.

For example, the in-coupling optical element 700 may be configured todeflect ray 770, which has a first wavelength or range of wavelengths.Similarly, the in-coupling optical element 710may be configured todeflect ray 780, which has a second wavelength or range of wavelengthsLikewise, the in-coupling optical element 720 may be configured todeflect ray 790, which has a third wavelength or range of wavelengths.

The deflected light rays 770, 780, 790 are deflected so that theypropagate through a corresponding waveguide 670, 680, 690; that is, thein-coupling optical elements 700, 710, 720 of each waveguide deflectslight into that corresponding waveguide 670, 680, 690 to in-couple lightinto that corresponding waveguide 670, 680, 690. The light rays 770,780, 790 are deflected at angles that cause the light to propagatethrough the respective waveguide 670, 680, 690 by TIR, and thus beguided therein. For example, deflection of the light rays 770, 780, 790may be caused by one or more reflective, diffractive, and/or holographicoptical elements, such as a holographic, diffractive, and/or reflectiveturning feature, reflector, or mirror. Deflection may in some cases becaused by microstructure such as diffractive features in one or moregratings, and/or holographic and/or diffractive optical elementsconfigured to turn or redirect light, for example, so as to be guidedwith the waveguide. The light rays 770, 780, 790 propagate through therespective waveguide 670, 680, 690 by TIR, being guided therein untilimpinging on the waveguide's corresponding light distributing elements730, 740, 750.

With reference now to FIG. 9B, a perspective view of an example of theset of stacked waveguides 660 of FIG. 9A is illustrated. As noted above,the in-coupled light rays 770, 780, 790, are deflected by thein-coupling optical elements 700, 710, 720, respectively, and thenpropagate by TIR and are guided within the waveguides 670, 680, 690,respectively. The guided light rays 770, 780, 790 then impinge on thelight distributing elements 730, 740, 750, respectively. The lightdistributing elements 730, 740, 750 may include one or more reflective,diffractive, and/or holographic optical elements, such as a holographic,diffractive, and/or reflective turning feature, reflector, or mirror.Deflection may in some cases be caused by microstructures such asdiffractive features in one or more gratings, and/or holographic and/ordiffractive optical elements configured to turn or redirect light, forexample, so as to be guided with the waveguide. The light rays 770, 780,790 propagate through the respective waveguide 670, 680, 690 by TIRbeing guided therein until impinging on the waveguide's correspondinglight distributing elements 730, 740, 750, where they are deflected,however, in a manner so that the light rays 770, 780, 790 are stillguided within the waveguide. The light distributing elements 730, 740,750 deflect the light rays 770, 780, 790 so that they propagate towardsout-coupling optical elements 800, 810, 820, respectively.

The out-coupling optical elements 800, 810, 820 are configured to directlight rays 770, 780, 790 guided within the respective waveguides 670,680, 690, out of the respective waveguides 670, 680, 690 and toward theviewer's eye. The out-coupling optical elements 800, 810, 820 may beconfigured therefore to deflect and redirect the light rays 770, 780,790 guided within the respective waveguides 670, 680, 690, at a morenormal angle with respect to the surfaces of the waveguides 670, 680,690 so as to reduce the effects of TIR such that light rays 770, 780,790 are not guided within the respective waveguides 670, 680, 690, butinstead exits therefrom. Moreover, these out-coupling optical elements800, 810, 820 may be configured to deflect and redirect light rays 770,780, 790 toward the viewer's eye. Accordingly, the out-coupling opticalelements 800, 810, 820 may include one or more reflective, diffractive,and/or holographic optical elements, such as a holographic, diffractive,and/or reflective turning feature, reflector, or mirror. Deflection mayin some cases be caused by microstructure such as diffractive featuresin one or more gratings, and/or holographic and/or diffractive opticalelements configured to turn or redirect the light rays 770, 780, 790 soas to be guided with the respective waveguide 670, 680, 690. The opticalelements 800, 810, 820 may be configured to reflect, deflect, and/ordiffract the light rays 770, 780, 790 so that they propagate out of therespective waveguides 670, 680, 690 toward the users eye.

In some embodiments, the light distributing elements 730, 740, 750 areorthogonal pupil expanders (OPE's). The OPE's may both deflect ordistribute light to the out-coupling optical elements 800, 810, 820 andalso replicate the beam or beams to form a larger number of beams whichpropagate to the out-coupling optical elements 800, 810, 820. As a beamtravels along the OPE's, a portion of the beam may be split from thebeam and travel in a direction orthogonal to the beam, in the directionof out-coupling optical elements 800, 810, 820. Orthogonal splitting ofthe beam in the OPE's may occur repeatedly along the path of the beamthrough the OPE's. For example, OPE's may include a grating having anincreasing reflectance along the beam path such that a series ofsubstantially uniform beamlets are produced from a single beam. In someembodiments, the out-coupling optical elements 800, 810, 820 are exitpupils (EP's) or exit pupil expanders (EPE's) that direct light in aviewer's eye 210 (FIG. 7). The OPE's may be configured to increase thedimensions of the eye box, for example, along the x direction, and theEPE's may be to increase the eye box in an axis crossing, for example,orthogonal to, the axis of the OPE's, e.g., along the y direction.

Accordingly, with reference to FIGS. 9A and 9B, in some embodiments, theset of stacked waveguides 660 includes waveguides 670, 680, 690,in-coupling optical elements 700, 710, 720, light distributing elements(e.g., OPE's), 740, 750, and out-coupling optical elements (e.g., EPE's)800, 810, 820 for each component color. The waveguides 670, 680, 690 maybe stacked with an air gap and/or cladding layer between each one. Thein-coupling optical elements 700, 710, 720 redirect or deflect incidentlight (with different in-coupling optical elements receiving light ofdifferent wavelengths) into its respective waveguide 670, 680, 690. Thelight then propagates at an angle which will result in TIR within therespective waveguide 670, 680, 690, and the light is guided therein. Inthe example shown, the light ray 770 (e.g., blue light) is deflected bythe first in-coupling optical element 700, and then continues topropagate within the waveguide 670 being guided therein, interactingwith the light distributing element (e.g., OPE's) 730 where it isreplicated into one or more rays propagating to the out-coupling opticalelement (e.g., EPE's) 800, in a manner described earlier. The light ray780 (e.g., green light) will pass through the waveguide 670, with thelight ray 780 impinging on and being deflected by the in-couplingoptical element 710. The light ray 780 then bounces down the waveguide680 via TIR, proceeding on to its light distributing element (e.g.,OPE's) 740 where it is replicated into one or more rays propagating tothe out-coupling optical element (e.g., EPE's) 810. Finally, the lightray 790 (e.g., red light) passes through the waveguides 670 and 680 toimpinge on the light in-coupling optical elements 720 of the waveguide690. The in-coupling optical elements 720 deflect the light ray 790 suchthat the light ray propagates to the light distributing element (e.g.,OPE's) 750 by TIR, where it is replicated into one or more rayspropagating to the out-coupling optical element (e.g., EPE's) 820 byTIR. The out-coupling optical element 820 then finally furtherreplicates and out-couples the light rays 790 to the viewer, who alsoreceives the out-coupled light from the other waveguides 670, 680.

FIG. 9C illustrates a top-down plan view (or front view) of an exampleof the set of stacked waveguides 660 of FIGS. 9A and 9B. As illustrated,the waveguides 670, 680, 690, along with each waveguide's associatedlight distributing element 730, 740, 750 and associated out-couplingoptical element 800, 810, 820, may be vertically aligned (e.g., alongthe x and y directions). However, as discussed herein, the in-couplingoptical elements 700, 710, 720 are not vertically aligned; rather, thein-coupling optical elements 700, 710, 720 are preferablynon-overlapping (e.g., laterally spaced apart along the x direction asseen in the top-down view of front view in this example). Shifting inother directions, such as the y direction, can also be employed. Thisnon-overlapping spatial arrangement facilitates the injection of lightfrom different resources such as different light emitters and/ordisplays into different waveguides on a one-to-one basis, therebyallowing a specific light emitter to be uniquely coupled to a specificwaveguide. In some embodiments, arrangements including non-overlappinglaterally-separated in-coupling optical elements 700, 710, 720 may bereferred to as a shifted pupil system, and the in-coupling opticalelements within these arrangements may correspond to sub-pupils.

In addition to coupling light out of the waveguides, the out-couplingoptical elements 800, 810, 820 may cause the light to be collimated orto diverge as if the light originated from an object at a far distanceor a close distance, depth, or depth plane. Collimated light, forexample, is consistent with light from an object that is far from theview. Increasing diverging light is consistent with light from an objectthat is closer, for example, 5-10 feet or 1-3 feet, in front of theviewer. The natural lens of the eye will accommodate when viewing anobject closer to the eye and the brain may sense this accommodation,which also then serves as a depth cue. Likewise, by causing the light tobe diverging by a certain amount, the eye will accommodate and perceivethe object to be at closer distance. Accordingly, the out-couplingoptical elements 800, 810, 820 can be configured to cause the light tobe collimated or to diverge as if the light emanated from a far or aclose distance, depth, or depth plane. To do so, the out-couplingoptical elements 800, 810, 820 may include optical power. For example,the out-coupling optical elements 800, 810, 820, may includeholographic, diffractive, and/or reflective optical elements that inaddition to deflecting or re-directing the light out of the waveguides,these holographic, diffractive, and/or reflective optical elements mayfurther include optical power to cause the light to be collimated ordiverging. The out-coupling optical elements 800, 810, 820 may in thealternative or in addition include refracting surfaces that includeoptical power that cause the light to be collimated or diverging. Theout-coupling optical elements 800, 810, 820 may therefore include, forexample, in addition to diffractive or holographic turning features, arefractive surface the provides optical power. Such refractive surfacemay also be included in addition to the out-coupling optical elements800, 810, 820, for example, on top of the out-coupling optical elements800, 810, 820. In certain embodiments, for example, optical elementssuch as diffractive optical elements, holographic optical elements,refractive lens surfaces, or other structures may be disposed withrespect to the out-coupling optical elements 800, 810, 820 to providethe optical power cause the collimation or divergence of the light. Alayer with optical power such as a layer with a refractive surface or alayer with diffractive and/or holographic features may for example bedisposed with respect to the out-coupling optical elements 800, 810, 820to additionally provide optical power. A combination of contributionsfrom both the out-coupling optical elements 800, 810, 820 having opticalpower and an additional layer with optical power such as a layer with arefractive surface or a layer with diffractive and/or holographicfeatures is also possible.

As illustrated in FIG. 9D, a specialized illumination system 900 mayprovide multiple input light rays 770, 780, 790 to the one or morein-coupling optical elements 700, 710, and 720. This illumination system900 illuminates a spatial light modulator 902 and directs the light rays770, 780, 790 to separate spatial locations corresponding to thelocation of the in-coupling optical elements 700, 710, and 720.

The illumination system 900 may be waveguide based and includes one ormore light emitters 904 configured to emit light and one or more lightturning optical elements comprising waveguides 906 disposed with respectto the one or more light emitters 904 to receive light from the one ormore light emitters 904. The received light is propagated within thelight turning optical elements, for example, guided within the one ormore waveguides 906 by TIR from the sides thereof.

The one or more waveguides 906 are also configured to eject light out ofthe one or more light turning optical elements comprising waveguides906. For example, the one or more light turning optical elementscomprising waveguides 906 may include a diffractive optical element, adiffraction grating, a holographic optical element, and/or ameta-surface configured to direct light out of the waveguide 906 ontothe spatial light modulator 902. The spatial light modulator 902 isdisposed with respect to the one or more waveguides 906 (for example, infront of or behind the one or more waveguides 906) to receive the lightejected from the one or more waveguides 906 and to modulate the receivedlight. In the example shown in FIG. 9D, the waveguide 906 is a frontlight design that is configured to turn light out rearward towards thespatial light modulator 902 that is rearward of the waveguide 906. Thislight ejected out of the waveguide 906 is incident on the spatial lightmodulator 902 and reflects therefrom, if the spatial light modulator 902is a reflective spatial light modulator. The spatial light modulator 902may include, for example, a reflective liquid crystal modulator (e.g.,liquid crystal on silicon (LCOS)), a digital light processing (DLP)micro mirror system, or other type of spatial light modulator. Thespatial light modulator 902 includes one or more pixels that can beindependently modulated to create, for example, an intensity pattern.For certain types of spatial light modulators 902, the spatial lightmodulator 902 modulates the polarization state of the light and, in someembodiments, a polarizer or other polarization selective optical elementtranslates the polarization modulation into an intensity modulation. Thespatial light modulator 902 may be in electrical communication withelectronics that drive the spatial light modulator 902 and controls thespatial light modulator 902 so as to form images. Electronics may alsocontrol the one or more light emitter 904 and coordinate the timing ofthe emissions provided by the one or more light emitter 904 such when alight of a given color illuminates the spatial light modulator 906 (viathe waveguide 906), the spatial light modulator 902 is driven to providethe proper pattern for that color. Imaging optics 908 may be disposedwith respect to the spatial light modulator 902 to received lighttherefrom and to image the intensity pattern (or image) formed by thespatial light modulator 902. Although a single positive power biconvexlens is shown to represent the imaging optics 908, the imaging optics908 may include more than one lens and need not be limited to a biconvexlens but may have other shapes, powers, configurations and opticalcharacteristics.

FIG. 9D shows a waveguide based image source 910 including the spatiallight modulator 902, the one or more light emitters 904 and the one ormore waveguides 906 and the imaging optics 908 configured to provideillumination. The spatial light modulator 902 is configured to modulatethe light from the illumination system 900 to yield an intensity image,and imaging optics 908 is configured to project the images formed by thespatial light modulator 902. Because this waveguide based image source910 utilizes one or more waveguides 906 to illuminate the spatial lightmodulator 902, the waveguide based image source 910 is thinner and thuslighter and more compact. Additionally, as a result of the waveguide 906being thin, the imaging optics 908 can be disposed closer to the spatiallight modulator 902. This allows the imaging optics 908 also to besmaller.

The one or more light emitters 904 can be configured to emit lighthaving a spectral distribution that includes spectral componentscorresponding to different colors such as red, green, and blue. The oneor more light emitters 904 may include light emitting diodes (LEDs),such as color LEDs like red, green, and blue LEDs. The waveguide basedimage source 910 can be configured such that the light of differentcolors (e.g., red, green, and blue) after being modulated by the spatiallight modulator 902 are directed along respective paths (e.g., pathscorresponding to light rays 770, 780, and 790) and are incident onrespective spatial locations (e.g., locations corresponding toin-coupling optical elements 700, 710, and 720) a distance from the oneor more waveguides 906 and the spatial light modulator 902.

The imaging optics 908 may, for example, a lens or lens system (e.g. aconvex lens) collimating or imaging light modulated by spatial lightmodulator 902.

As illustrated in FIG. 9D, the set of stacked waveguides 660 is disposedto receive the light rays 770, 780, 790 from the waveguide based imagesource 910. In particular, FIG. 9D shows the first waveguide 670 and thein-coupling optical element 700 (e.g., for receiving red light from theimage source 910), the second waveguide 680 and the in-coupling opticalelement 710 (e.g., for receiving green light from the image source 910),and the third waveguide 690 and the in-coupling optical element 720(e.g., for receiving blue light from the image source 910). Each ofthese in-coupling optical elements 700, 710, 720 are disposed withrespect to the respective paths for the light rays 770, 710, 720 (e.g.,red, green, and blue light rays) and at the suitable spatial location toreceive the light modulated by the spatial light modulator 902 thatforms respective red, green and blue images.

Although red, green, and blue color lights are used as examples, othercolor light may be employed. Accordingly, the one or more light emitters904 may emit different color light and the one or more waveguides 906may propagate different color light. Additionally, although threecolors, red, green, and blue are described above as examples, more orless colors may be used. For example, if only two colors are used,possibly less light emitters 904 and less waveguides 906 may beemployed.

In various designs, these systems and components are relatively compactto be disposed in a display device for a head mounted display. The setof stacked waveguides 660 may include a pupil expander such as describedabove. Additionally, the waveguides 670, 680, 690 may be opticallytransparent so that a viewer can see through the waveguides 670, 680,690, for example, in the head mounted display.

Various designs of the waveguide based image source 910 may be used todeliver different color light (e.g., red, green, and blue) to theseparate spatial locations where the respective in-coupling opticalelements 700, 710, 720 are situated. For example, a single waveguide,e.g. waveguide 906, may receive white light and include an out-couplingoptical element that has dispersion and that directs different colorlight (red, green, blue) into different directions. This may reduce theneed to provide separate waveguides for transmission of differentcolors. In some embodiments, one or more waveguides each opticallycoupled to a different color LED (red, green, blue) may haveout-coupling optical elements that direct the light in the respectivewaveguides into different directions. In some embodiments, a singlewaveguide may be coupled to a white LED and out-couple the light to oneor more shutters with corresponding color filters to selectively passdifferent colors of light at different times. The shutters and filtersare at different lateral positions so as to create color beams that areat different lateral positions. Alternatively, a single waveguide may becoupled to a white LED and out-couple the light to one or more dichroicbeam splitters that split the different colors and produces differentcolor beams that are at different lateral positions. Other designs arealso possible.

FIG. 10A, for example, illustrates a display device 1000 that includes asingle waveguide 1010 that is disposed with respect to a white lightsource (or emitter) 1002 to receive white light and includes anout-coupling optical element 1014 that has dispersion. The out-couplingoptical element 1014 may include a grating or diffractive opticalelement that has dispersion. The dispersion may cause the out-couplingoptical element 1014 to act differently for different wavelength light.The dispersion may cause the out-coupling optical element 1014 toredirect light of different colors at different angles. Accordingly, thedispersion may cause the out-coupling optical element 1014 to directdifferent color light (red, green, blue) into different directions andalong different optical paths such that different color light isincident on different spatial locations.

In this example, the waveguide 1010 is configured to front-light thespatial light modulator 1018. The light source 1002 is disposed withrespect to an edge of the waveguide 1010 to couple light into thewaveguide 1010 through that edge. A coupling lens 1009 is includedbetween the light source 1002 and the edge of the waveguide 1010 toassist in coupling light from the light source 1002 into the waveguide1010. In some embodiments, the coupling lens 1009 may be excluded, andthe light source 1002 may be positioned closer to the edge of thewaveguide 1010 to couple light therein.

This light source 1002 may have a spectral distribution that includesspectral components corresponding to one or more different colors. Thespectral distribution, for example, may include multiple spectral peaksthat separately correspond to colored light such as red, green, or bluelight or may otherwise include multiple spectral components thatindividually correspond to different colors. Accordingly, the lightemitted from the light source 1002 may be polychromatic and possiblybroad band, such as in the case of white light. The dispersion in theout-coupling element 1014 may be used to separate these different colorspectral components. In the embodiment illustrated in FIG. 10A, thewhite light source 1002 may be a white LED.

The waveguide 1010 may include a sheet or film of material that isoptically transmissive material to the wavelength of light output by thelight source 1002, which may be visible light. In various designs, thewaveguide 1010 is transparent to visible light. Accordingly, thewaveguide 1010 may be employed in an eyepiece of an augmented realityhead mounted display through which the viewer views the world. Lightinjected into the edge of the waveguide 1010 by the light source 1002may be guided in the waveguide by TIR.

The out-coupling optical element 1014 may be included in or on thewaveguide 1010, for example, on one or more major surfaces of thewaveguide 1010. As illustrated in FIG. 10A, the out-coupling opticalelement 1014 is disposed on a side of the waveguide 1010 farther fromthe spatial light modulator 1018 although the out-coupling opticalelement 1014 may located on the side closest to the spatial lightmodulator 1018. The out-coupling optical element 1014 may include one ormore diffractive, and/or holographic optical elements includingdiffractive or holographic features. The out-coupling optical element1014 may include one or more gratings or holograms. Accordingly, theout-coupling optical element 1014 may include turning features such asdiffractive features or microstructure configured to turn the lightguided within the waveguide 1010 out of the waveguide 1010. The turningfeatures, microstructure, and/or the out-coupling optical element 1014may be reflective (although the turning features and/or the out-couplingoptical element 1014 may operate in transmission, turning light that istransmitted through the out-coupling optical element 1014 in certaincases). In some embodiments, the out-coupling optical element 1014 mayinclude surface features that are smaller or similar in size as thewavelength light input into the waveguide 1010 by the light source 1002.As discussed above, the out-coupling optical element 1014 may havedispersion that acts on different color light differently. In somecases, the out-coupling optical element 1014 may be a wavelengthselective optical element, advantageously allowing preferentialout-coupling of light of a particular wavelength or color, thus allowingcontrol of the position and/or angle of out-coupled light based onwavelength or color. One or more such out-coupling optical elements 1014may be included in the waveguide 1010.

Deflection may be caused by the turning features in the out-couplingoptical element 1014 that are configured to turn or redirect lightguided within the waveguide 1010. As illustrated by a ray of light 1006,the out-coupling optical element 1014 may be configured to reflect,deflect, and/or diffract the ray 1006 from the light source 1002 that isguided within the waveguide 1010 so that it propagates out of thewaveguide 1010 toward the spatial light modulator 1018.

The spatial light modulator 1018 may include a spatial light modulatorof various types, such as an liquid crystal on silicon (LCOS), digitallight processing (DLP) device (e.g. a micromirror array), or an e-paperdevice. Other types of spatial light modulators may also be used. Asappropriate, the spatial light modulator 1018 may be operated inreflection mode or in transmission mode and may be located in the pathof the light ejected out of the waveguide 1010 as appropriate. Incertain display devices, the spatial light modulator 1018 including aLCOS is operated in reflective mode. LCOS and various other spatiallight modulators such as certain liquid crystal based spatial modulatorsmodulate the polarization state of the light. For example, a pixel inthe spatial light modulator 1018 may rotate or not rotate a polarizationstate, such as a linear polarization state, depending on the state ofthe pixel. Accordingly linearly polarized light having one state (e.g.,an s state) may be selectively rotated (e.g., to a p state or viceversa) depending on the state of the pixel (e.g., on or off or viceversa). A analyzer or polarizer 1022 may be used to filter out light ofone of the polarization states transforming the polarization modulationinto intensity modulation that forms an image.

Accordingly, the display device 1000 may include a polarizer 1008 tocause the light from the light source 1002 that is injected into thewaveguide 1010 to be polarized (e.g., in the s state). In some cases,the polarizer 1008 may be excluded, for example, if the light source1002 outputs polarized light.

As discussed above, an analyzer 1022 may be included in an optical pathbetween the spatial light modulator 1018 and the output of the imagesource (e.g. ray of light 1006). The analyzer 1022 may be particularlyuseful if the spatial light modulator 1018 modulates the polarizationstate of the light incident thereon. The analyzer 1022 may be configuredto attenuate light of one polarization state in comparison to anotherpolarization state. Accordingly, the analyzer 1022 may vary theintensity of the light based on the polarization state of the light,which may be dependent on the polarization modulation produced by thespatial light modulator 1018. In FIG. 10A, the analyzer 1022 is showndisposed between the spatial light modulator 1018 and the waveguide 1010and the out-coupling optical element 1014 such that out-coupled light1016 a, 1016 b 1016 c passes through the analyzer 1022 onto the spatiallight modulator 1018, which in the configuration shown in FIG. 10Aoperates in reflective mode, and passes again through the analyzer 1022after reflection from the spatial light modulator 1018. Out-coupledintensity modulated light 1016 a, 1016 b 1016 c may then propagatetowards an in-coupling element for an eyepiece (not shown), such asin-coupling element 700, 710, 720 as discussed herein with reference toFIG. 9B.

FIG. 10A shows as an example, the ray of light 1006 output by the lightsource 1002 that pass through the polarizer 1008 to provide a definedpolarization state, such as a linear polarization state such as spolarization (or horizontally polarized light). The ray of light 1006may then be in-coupled into waveguide 1010 via the in-coupling opticalelement 1009. The ray of light 1006 then propagates within the waveguide1010 by TIR off the major surfaces (e.g., top and bottom or forward andrearward surfaces) of the waveguide 1010 and is incident on theout-coupling optical element 1014 one or more times. The out-couplingoptical element 1014 may be configured to deflect and redirect the rayof light 1006 guided within the waveguide 1010 at a more normal anglewith respect to the major surfaces of the waveguide 1010 so as to reducethe effects of TIR such that light is not guided within the waveguide1010 but instead exits therefrom. Moreover, out-coupling optical element1014 may be configured to deflect and redirect this this light towards aspatial light modulator 1018.

The ray of light 1006 is a representative example of a ray of light 1006from the light source 1002 that is guided within the waveguide 1010. Forexample, a cone of such rays may be emitted by the light source 1002 andpropagated within the waveguide 1010. Similarly, each if the rays ofout-coupled light 1016 a, 1016 b 1016 c is a representative example ofone ray out of a large number of rays that may be out-coupled over thelength of out-coupling optical element 1014 at various locations on thewaveguide 1010 and the out-coupling optical element 1014 and at variousangles, depending on the angle of the ray incident thereon. Theout-coupling optical element 1014 may be configured to out-couple theray of light 1006 at multiple locations over the length of the waveguide1010, thus creating many rays of out-coupled light, such as rays ofout-coupled light 1016 a, 1016 b 1016 c

The angle of the ray out-coupled from the waveguide 1010 may depend inpart on the design of the out-coupling optical element 1014. In FIG.10A, the angle between the out-coupled ray of light 1016 and a surfacenormal of waveguide 1010 is designated as angle β. In various cases,this angle β also corresponds to the angle at which the ray of lightreflects from the spatial light modulator 1018 and propagates againthrough the waveguide 1010, and away from the image source 910. Based onthe design of the display device 1000 and, for example, the out-couplingoptical element 1014, this angle, β, may be affected by the wavelengthof the ray of light 1016 (as well as the characteristics of out-couplingoptical element 1014 such as the diffraction grating spacing for adiffraction grating). For example, for out-coupling optical elementsincluding diffractive features, the out-coupling optical element 1014may exhibit dispersion and the angle β may vary with wavelength. In FIG.10A, this effect is shown by rays 1016 a, 1016 b, 1016 c, which areintended to correspond to different colors such as red, green, and blueor blue, green, and red, and that are diffracted at different angles β.

Accordingly, by appropriately controlling angle β for differentwavelengths, out-coupled light of different wavelengths may be spatiallyseparated. Light of multiple wavelength or colors (e.g., red, green, andblue) may thus be introduced into the waveguide 1010 and be directedalong different paths (e.g., at different angles) to different spatiallocations a distance from the waveguide 1010 and spatial light modulator1018. The in-coupling optical elements 700, 710, 720 may be located atthese respective spatial locations where the different wavelengths orcolors (e.g., for red, green, and blue light) are located such thatdifferent colors are coupled into different in-coupling optical elementsand different waveguides 670, 680, 690 in the set of stacked waveguides660 in the eyepiece.

As discussed above, the out-coupled light 1016 corresponds to just asingle ray of light emitted from the light source 1002, however, a coneof similar rays may be output by emitter. Likewise, a cone of rays foreach color may be out-coupled from the waveguide 1010 using theout-coupling optical element 1014 and directed to the spatial lightmodulator 1018. These rays may be modulated by the spatial lightmodulator 1018 and may propagate away from imaging source 910.

FIG. 10B shows one or more cones of light of different color propagatingaway from the imaging source 910. In various implementations, the lightemitted by the light source 1002 will diverge and have a divergenceangle. This light will propagate within the waveguide 1010 and be turnedby the out-coupling optical element 1014, interact with the spatiallight modulator 1018 and propagate therefrom, through the waveguide 1010and the out-coupling optical element 1014, still diverging. As a result,FIG. 10B shows diverging light, for example, cones of light rays, 1016a, 1016 b, and 1016 c. The light source 1002 may output light includingmultiple spectral components (e.g., spectral peaks) associated withdifferent colors. The light source 1002 may, for example, be a broadband light source such as a white LED (WLED) including red, green andblue spectral peaks. As a result of dispersion in the illuminationsystem 900, for example, in the out-coupling optical element 1014, thedifferent color light emitted by the light source 1002 exits the systemas out-coupled cones of light 1016 a, 1016 b and 1016 c that aredirected away from the waveguide 1010 in different directions. Forexample, out-coupled light 1016 a (e.g. red) may be propagating awayfrom the waveguide 1010 along a first path directed at a first angle(e.g., centered about a positive angle with respect to the normal),whereas out-coupled light 1016 b (e.g., green) may be propagating awayfrom the waveguide 1010 along a second path directed at a second angle(e.g., centered about an angle normal to the waveguide), and out-coupledlight 1016 c may be propagating away from the waveguide 1010 along athird path directed at a third angle (e.g., centered about a negativeangle with respect to the normal). This dispersive effect of theillumination system 900 introduced, for example, by using anappropriately designed out-coupling element 1014 may facilitate thespatial separation of various colors or wavelengths of the out-coupledlight 1016 a, 1016 b, 1016 c. This particular arrangement of colors andoutput angles is only an example and the color, order, and the relativeor particular angles may be different.

Another approach is to employ one or more waveguides 1010 each opticallycoupled to a different color emitter (e.g., a red LED, a green LED, anda blue LED) and including out-coupling optical elements 1014 that directthe light guided in the respective waveguides into different directions.FIGS. 11A-11C, for example, illustrates first, second, and third lightsources 1102 a, 1102 b, 1102 c optically coupled to respective, first,second, and third waveguides 1110 a, 1110 b, 1110 c via respectivefirst, second, and third in-coupling elements 1109 a, 1109 b, 1109 c.Polarizers 1108 a, 1108 b, 1108 c may be disposed in the beam pathbetween the respective light sources 1102 a, 1102 b, 1102 c andrespective waveguide 1110 a, 1110 b, 1110 c to provide a particularpolarization such as the s-polarization state, and an analyzer 1122 maybe disposed between first, second and third waveguides 1110 a, 1110 b,1110 c and spatial light modulator 1118. The multiple light sources 1102a, 1102 b, 1102 c may have different spectral profiles and outputdifferent color light such as red, green, and blue light. For example,the first light emitter 1102 a may couple blue color light into thefirst waveguide 1110 a, the second light emitter 1102 b may couple greencolor light into the second waveguide 1110 b and the third light emitter1102 c may couple red color light into the third waveguide 1110 c. Thefirst, second, and third waveguides 1110 a, 1110 b, 1110 c includerespective first, second, and third, out-coupling elements 1114 a, 1114b, 1114 c configured to direct light along respective first, second, andthird optical paths to respective first, second, and third spatiallocations. The first, second, and third out-coupling optical elements1114 a, 114 b, 114 c may include different diffraction gratings,holograms, diffractive optical elements, microstructure, or otherstructures or features that operate on light propagating at differentangles in the different waveguides 1110 a, 1110 b, 1110 c so as todirect the light into different directions. The out-coupling opticalelements 1114 a, 1114 b, 1114 c may be configured to reflect, deflect,and/or diffract the light rays from the respective light sources 1102 a,1102 b, 1102 c that are guided within the respective waveguides 1110 a,1110 b, 1110 c, based on polarization state of the light rays, so thatthe light rays propagate out of the waveguides 1110 a, 1110 b, 1110 ctoward a spatial light modulator 1118. The out-coupling optical elements1114 a, 1114 b, and 1114 c may be further configured to pass orotherwise transmit light rays from the spatial light modulator 1118,based on polarization state of the light rays, out of the image source910. FIG. 11A shows out-coupled light 1116 a corresponding to a firstcolor 1106 a (e.g., blue) from the first waveguide 1110 a directed alongthe first direction/optical path. FIG. 11B shows out-coupled light 1116b corresponding to a second color 1106 b (e.g., green) from the secondwaveguide 1110 b directed along the second direction/optical path, andFIG. 11C shows out-coupled light 1116 c corresponding to a third color1106 c (e.g., red) from the third waveguide 1110 c directed along thethird direction/optical path. This configuration allows multiplewaveguides 1110 a, 1110 b and 1110 c to be stacked and to spatiallyseparate the different wavelengths of out-coupled light. The respectiveangles of the cones of out-coupled light 1116 a, 1116 b and 1116 c maybe negative, zero, or positive; however, the angles, the order, and thecolors may be different.

FIG. 11D shows another configuration, similar to the display deviceshown in FIGS. 11A-11C, however, two of the colors are combined into asingle waveguide. In FIG. 11D, for example, first, second, and thirdlight sources 1102 a, 1102 b, 1102 c, are shown optically coupled intofirst and second waveguides 1110 a, 1110 b. In particular, the firstlight source 1102 a outputting light of a first color is coupled intothe first waveguide 1110 a, and the second and third light sources 1102b and 1102 c, which output second and third color light, respectively,are coupled to the second waveguide 1110 b. The first and secondwaveguides 1110 a, 1110 b include first and second out-coupling elements1114 a, 1114 b, respectively, configured to direct light alongrespective first and second optical paths to respective first and secondspatial locations. The first and second out-coupling elements 1114 a,1114 b may include different diffraction gratings, holograms,diffractive optical elements, microstructure, or other structures thatoperate on light propagating at different angles in the differentwaveguides so as to direct the light into different directions. Theout-coupling optical elements 1114 a, 1114 b may be configured toreflect, deflect, and/or diffract the light rays from the light sources1102 a, 1102 b, 1102 c that are guided within the respective waveguides1110 a, 1110 b, based on polarization state of the light rays, so thatthe light rays propagate out of the waveguides 1110 a, 1110 b toward thespatial light modulator 1118. The out-coupling optical elements 1114 a,1114 b may be further configured to pass or otherwise transmit lightrays from the spatial light modulator 1118, based on polarization stateof the light rays, out of the image source 910.

FIG. 11D, for example, shows out-coupled light 1116 b corresponding tothe light having a different spectral distribution resulting from thecombination of light from the second and third light sources 1102 b,1102 c (e.g., the combination of red and blue light from red and blueemitters) ejected from the second waveguide being directed along thesecond direction/optical path. The out-coupled light 1116 acorresponding to the first color (e.g., green) from the first waveguide1110 a can be directed to an in-coupling optical element 710 located atthe first spatial location. The out-coupled light 1116 b correspondingto the light having a different spectral distribution resulting from thecombination of different color light from the second and third lightsources 1102 b, 1102 c (e.g., the combination of red and blue light fromred and blue light sources) ejected from the second waveguide 1110 b canbe directed to respective in-coupling optical elements 700 and 720located at the second spatial location laterally displaced with respectto the first location and in-coupling optical element 710. Thein-coupling optical element 720 that receives the light having adifferent spectral distribution resulting from the combination of lightfrom the second and third light sources 1102 b, 1102 c (e.g., thecombination of red and blue light from red and blue light sources) mayinclude a dichroic element that directs light having one spectralprofile in one direction and directs light having another spectralprofile in a different direction Likewise, light from the second lightsource 1102 b may be separated from light from the third source 1102 c.The dichroic element may direct the light of the second and third colors(e.g., red and blue light from the red and blue emitters) into differentwaveguides. In another configuration, in-coupling optical element 700and 720 may be combined into a signal dichroic incoming optical elementthe couples light into one waveguide (e.g., waveguide 670) or anotherwaveguide (e.g., one of waveguides 670, 690) based on the wavelength.

Other approaches to illuminating the spatial light modulator 1018 arepossible. FIG. 12A illustrates another display device, like the displaydevice in FIG. 10A and 10B, wherein a single waveguide 1010 is coupledto a light source (e.g., a white LED) 1002 that emits one or more colorcomponents. Light from the light source 1002 is out-coupled from thewaveguide 1010 onto a spatial light modulator 1018 by an out-couplingoptical element 1014. After modulation, light is directed to one or moreshutters with corresponding color filters to selectively pass differentcolors of light at different times.

FIG. 12A shows a shutter unit 1212 that includes one or moreelectronically controlled shutters 1216 a, 1216 b and 1216 c andassociated color filters 1215 a, 1215 b, 1215 c. FIG. 12A shows, forexample, first, second, and third shutters 1216 a, 1216 b and 1216 c,aligned with corresponding first, second, and third color filters 1215a, 1215 b, 1215 c, forming respective first, second, and third channels,which may selectively transmit first, second, and third colors,respectively. The shutter unit 1212 may include, for example, acolor-selective liquid crystal (LC) shutter unit. The filters mayinclude a variety of filters including absorption filters and/orinterference filters. Although three channels are shown in FIG. 12A, adisplay device 1000 may include more channels or less channels.

The shutters 1216 a, 1216 b and 1216 c and filters 1215 a, 1215 b, 1215c are disposed with respect to the waveguide 1010 and the spatial lightmodulator 1018 so as to receive light 1016 output from the waveguide andmodulated by the spatial light modulator 1018. FIG. 12A also showsimaging optics 1244 that projects light from the spatial light modulator1018 onto the shutter unit 1212.

The shutter unit 1212 and the spatial light modulator 1018 may be inelectrical communication with control electronics 1240, which maycontrol the opening and closing of the shutters 1216 a, 1216 b and 1216c. The control electronics 1240, which may include a clock circuit whichmay synchronize the opening and closing of the shutters 1216 a, 1216 band 1216 c to the operation (e.g., refresh) of the spatial lightmodulator 1018.

The shutter unit 1212 may be operated in synchronization with thespatial light modulator 1018 so that at any given time, no more than onechannel on the shutter unit 1212 is open. The time during which achannel on the shutter 1212 remains open may be referred to as dwelltime. In various examples, the shutter unit 1212 may include threechannels corresponding to a tricolor stimulus (e.g. red color filter1215 a, green color filter 1215 b and blue color filter 1215 c). Forexample, the spatial light modulator 1018 may be set to an outputpattern corresponding to the red component of an image, while shutterunit 1212 opens the red channel and keeps the green channel and the bluechannel closed, thus only permitting red light to pass. The spatiallight modulator 1018 may correspondingly be set to an output patterncorresponding to the green component of an image, while simultaneously,shutter unit 1212 keeps red channel and blue channel closed and opensthe green channel, thus only allowing green light to pass. The spatiallight modulator 1018 may then be set to an output pattern correspondingto the blue component of an image, while shutter 1212 keeps greenchannel and red channel closed and opens blue channel, thus onlyallowing blue light to pass.

FIG. 12B is a block diagram that illustrates an example refresh cycle ofsystem of a display device including a shutter unit. In block 1250, thesystem begins a refresh by closing all shutter channels. After allshutter channels have been closed, the spatial light modulator 1018transitions to displaying the modulation pattern for the first colorcomponent, e.g. red, in block 1254. When the spatial light modulator1018 has finished the switching process and thus established theappropriate modulation pattern for the first color component, the redshutter channel is opened in block 1258, thus allowing red light to passtowards the eyepiece, however blocking green and blue light. In block1262, the system remains in this state for the dwell time correspondingto the red color component. After the dwell time has elapsed, the systemproceeds to block 1266, closing the red shutter channel. When the redshutter channel has been closed, the spatial light modulator 1018transitions to the output a pattern corresponding to the second colorcomponent, e.g., green, in block 1270. When the spatial light modulator1018 has finished its switching process, the green shutter channel isopened in block 1274, thus permitting green light to pass towards theeyepiece, however, blocking red and blue light. The system then remainsin this state and waits in block 1278 until the dwell time for the greencolor component has elapsed. The system then proceeds to close the greenshutter channel in block 1282. When the green shutter channel has beenclosed, the spatial light modulator 1018 transitions to the modulationpattern corresponding to the third color component, e.g., blue, in block1286. After the spatial light modulator 1018 has finished its switchingprocess, the blue shutter channel 1290 is opened in block 1290. Bluelight is passed while red and green light are blocked. In block 1294,the system then remains in this state until the blue dwell time haselapsed. The system may then return to block 1250, starting the nextrefresh cycle. Other system configurations as well as process flows arepossible.

FIG. 13 depicts another design for a display device 1000 that, like thedisplay device 1000 shown in FIG. 12A, including a single waveguide 1010that may be coupled to a light source 1002 that outputs light includingone or more spectral components that correspond to multiple colors.Instead of out-coupling light from the waveguide 1010 onto a spatiallight modulator 1018 and then to a shutter unit 1212, one or moredichroic beam splitters are used to split the different colors andproduces different color beams that at different lateral positions.

The light source 1002 may include, for example, a white LED. The source1002 is disposed with respect to the waveguide 1010 to couple lighttherein. The waveguide 1010 includes an out-coupling element 1414 thatextracts light and cause the extracted light to be incident on a spatiallight modulator 1018.

The display device 1000 further includes a beam splitter assemblydisposed with respect to the waveguide 1010 and the spatial lightmodulator 1018 to receive light therefrom. The beam splitter assemblyincludes a first dichroic beam splitter 1412, a second dichroic beamsplitter 1408, and a third reflective surface 1404. The beam splitterassembly 1402 is configured to separate out individual color components.For example, if the incident beam includes first, second and thirdcolors, e.g., red, green and blue, the first beam splitter 1412 mayinclude a dichroic reflector that transmits the first color and reflectsthe second and third colors. The second beam splitter 1408 may alsoinclude a dichroic reflector that reflects the second the color andtransmits the third color. The reflective surface 1404 may redirect thethird remaining color such that the first, second, and third color beams770, 780, 790 are directed toward in-coupling optical elements 700, 710,and 720, respectively.

For example, as shown in FIG. 13, a ray of light 1006 from the broadband light source 1002, which may include a white LED, may be coupledinto the waveguide 1010 and out-coupled by the out-coupling element 1414towards a spatial light modulator 1018. The out-coupling element 1414may be configured to reduce dispersion in the out-coupled beam 1402.After being reflected from spatial light modulator 1018, the modulatedbeam is directed towards the first beam splitter 1412 that selectivelypasses or directs light of a specific color (e.g. blue light) towards aspecific optical path, while reflecting or directing light not of thespecific color along another optical path (e.g. the remaining red andgreen components in out-coupled beam 1402). The beam transmitted throughthe first beam splitter 1412 may form light ray 770 and may be directedtowards an in-coupling optical element, such as in-coupling element 700,for another waveguide 670 in the eyepiece element, as discussed withreference to FIG. 7. The reflected beam 1410 travels towards the secondbeam splitter 1408 that selectively directs or reflect light of anotherspecific wavelength or color (e.g. green light) along a specific opticalpath, while transmitting or directing light not of the specificwavelength (e.g. the remaining blue component). The beam reflected fromthe second beam splitter 1408 may form light ray 780 and may be directedtowards an in-coupling optical element, such as in-coupling element 710,for another waveguide 680 in the eyepiece element, as discussed withreference to FIG. 7. The beam 1406 transmitted though beam splitter 1408propagates towards the reflective surface 1404, where it may bereflected. The reflected beam 790 may then travel towards an in-couplingoptical element 720 for another waveguide 690 in the eyepiece element,such as in-coupling optical element 720, as discussed with reference toFIG. 7. Other configurations are possible. For example, more or lessbeam splitters may be included in the beam splitter assembly and thearrangement may be different.

Although illumination systems may be described above as waveguide basedand comprising one or more waveguides, other types of light turningoptical elements may be employed instead of a waveguide. Such lightturning optical elements may include turning features to eject the lightout of the light turning optical element, for example, onto the spatiallight modulator. Accordingly, in any of the examples described herein aswell as any of the claims below, any reference to waveguide may bereplaced with light turning optical element instead of a waveguide. Sucha light turning optical element may comprise, for example, a polarizingbeamsplitter such as a polarizing beamsplitting prism.

Additional Variations

The various devices, system, configurations, methods, and approachesabove can be implemented in a wide variety of ways. For exampledifferent types of outcoupling optical elements may be employed. Invarious implementations, for example, the outcoupling optical elementmay include a volume phase grating or hologram. Reflective volumegrating, for example, exhibit strong directional diffraction as well ashigh coupling efficiency (e.g., up to about 100% efficiency). Also,different schemes for introducing light into the waveguide are possible.

FIGS. 14A and 14B illustrate different configurations for providinglight from a light source 1002 to a waveguides 1010 for front-lighting aspatial light modulator. In FIG. 14A, the light source 1002 is anapproximately “point” light source (e.g., an LED), wherein, a least to areasonable approximation for the application, all rays divergesubstantially from a single point. In FIG. 14B, the light source 1002 isan “extended” light source that substantially extends along at least onespatial dimension, for example, as illustrated, along the length of aside of the waveguide 1010. The light source 1002 may be a line lightsource or area light source or part thereof. For example, the lightsource 1002 may include a linear arrangement of LEDs, for example,micro-LEDs, which may have microlens arrays for beam shaping. In someembodiments, light source 1002 may extend over the entire cross-sectionof the interface between waveguide 1010 and the surrounding medium, orthe light source 1002 may extend over 90%, 80%, 70%, 60%, 50%, 40%, 30%or less than 30% of the cross-sectional area of the side of thewaveguide 1010 in which light from the light source 1002 is injected.

In some embodiments, light-coupling optics 1011 may be disposed betweenthe light source 1002 and the waveguide 1010 and may be employed tofacilitate coupling of light from the light source 1002 into thewaveguide 1010. The waveguide 1010 may include a thin opticaltransparent slab (e.g., glass or plastic) having for example a thicknessranging from 0.1 mm to 5 mm.

FIGS. 14C-14E illustrate arrangements for coupling light from a lightsource 1022 into a waveguide 1010, according to some embodiments. Inparticular, FIGS. 14C-14E depict waveguides 1010 for front-lighting aspatial light modulator (SLM) 1018 having a side light distributor forcoupling light from a light source 1002 into the waveguides 1010. FIG.14C illustrates an arrangement wherein a separate side light distributorincluding a light guide 1099 a directs light into the waveguide 1010. Anoutcoupling optical element such as a grating is disposed in or on thelight guide 1099 a and is configured to redirect the light propagatingwithin the light guide 1099 a such that the light exits the light guide1099 a. An optional reflective element 1099 b may be disposed withrespect to the light guide 1099 a and the grating to reflect lighttoward the waveguide 1010. Accordingly, the light emitted from lightsource 1002 is injected into a light guide 1099 a and directed out ofthe light guide into waveguide 1010 for front lighting a SLM 1018.

FIG. 14D illustrates a waveguide 1010 having a side light distributor.At one end of the waveguide 1010, side light distributor including aturning element is provided. This turning element rotates thepropagation of a beam of light from the light source 1002 that iscoupled into an edge of the waveguide 1010. As illustrated, light fromthe light source 1002 propagates within the waveguide 1010 along an edgeor side thereof. The turning element rotates this beam in someimplementations 90° away from the side of the waveguide 1010 and furtherinto the waveguide 1010. The turning element may, for example, include adiffraction grating. In some implementations, the diffraction gratingmay have a grating vector that is 45° with respect to the beampropagation direction along the side of the waveguide 1010. FIG. 14Eshows a side cross-sectional view of the side light distributor. Lightfrom the light source 1002 propagates within the waveguide 1010, forexample, via total internal reflection form top and bottom surfaces ofthe waveguide 1010. Light incident on the turning element including, forexample, the diffraction grating is turned, possible about 90° from thebeam propagation direction. This redirection of the light is illustratedin FIG. 14E as light coming out of the paper. Other configurations arepossible.

An outcoupling optical element 1014 may be used to couple lightpropagating within the waveguide 1010 out of the waveguide 1010 towardthe SLM 1018. The light may propagate within the waveguide 1010 viatotal internal reflection. When the light interacts with the outcouplingoptical element 1014, which may include, for example, a diffractiongrating on a surface of the waveguide 1010, light is coupled out of thewaveguide 1010 toward the SLM 1018. This grating may include a volumephase grating. Similarly, volume phase holograms or other volumediffractive optical elements may be employed in various implementations.

FIG. 15A shows a cross section of a waveguide 1010 having an outcouplingoptical element 1014 including a volume phase grating thereon, accordingto some embodiments. This volume phase grating includes a reflectivevolume phase grating. Accordingly light diffracted by the reflectivevolume phase grating is diffracted and reflected toward the SLM 1018 forproviding illumination thereto.

In various implementations, the outcoupling optical element 1014 mayhave a gradient in coupling efficiency (e.g., grating efficiency ordiffraction efficiency) that increases with distance away from the lightsource 1002. This gradient is represented by an arrow 1075 in FIG. 15A.As light is coupled out of the waveguide 1010, the light within thewaveguide 1010 is depleted. By increasing the coupling efficiency atlocations farther away from the light source, this depletion in lightwithin the waveguide 1010 can be offset. Accordingly, relatively lowercoupling efficiency is provided closer to the light source 1002, whilehigher coupling efficiency is provided farther from the light source1002. A more uniform distribution of light can therefore be providedacross the SLM 1018. Accordingly, the coupling efficiency at differentlocations across the outcoupling optical element 1014 can be optimizedor modified to increase uniformity in light distribution across the SLM1018.

In some implementations, the outcoupling optical element 1014 includes agrating wherein the grating has a variation, for example, a gradient, inpitch. For example, the grating pitch may increase with distance awayfrom the light source 1002. This variation in pitch will alter theangles at which light is coupled out based on the location on thewaveguide 1010 and grating where the light is coupled out. Areas of thegrating of the outcoupling optical element 1014 closer to the lightsource 1002 may couple out light at lower angles while areas fartherfrom the light source 1002, (e.g., at the other the end of the waveguide1010) couple out light at high angles; the pitch may thus decrease alongthe direction indicated by arrow 1075 Using such a gradient pitch withhigh coupling efficiency, the illumination beam can be shaped while itpropagates in the waveguide 1010.

Since volume phase gratings may exhibit narrow spectral and angularproperties, one or more volume phase gratings or stack of volume phasegratings may be used in various embodiments. FIG. 15B illustrateswaveguide-based light distribution device with a waveguide 1010 and astack 1087 of volume phase grating (VPG) diffractive elements forcoupling light out of the waveguide 1010. The stack 1087 may includevarious volume phase grating diffractive elements configured to diffractlight having different wavelengths. Moreover, the stack 1087 may includevarious VPG diffractive elements configured to diffract light havingdifferent colors. For example, the stack 1087 may include multiple (e.g.three) volume phase gratings, different gratings associated withwavelengths corresponding to different colors, respectively (e.g., red,green and blue). Light may be outcoupled at different locations at thestack 1087, as exemplified in the drawing by a first outcoupled cone1088 a and a second outcoupled cone 1088 b originating from differentlocations in stack 1087.

Alternatively or additionally, as illustrated in FIG. 15C, the stack1087 may include multiple volume phase gratings for the same color, butthat diffract light at different angles. For example, the stack 1087 mayinclude a first volume phase grating associated with a wavelengthcorresponding to the color red, a second volume phase grating associatedwith the same or another wavelength corresponding to the color green,and a third volume phase grating associated with the same or yet anotherwavelength corresponding to the color blue. However, the differentgratings in the stack 1087 may diffract the light such that the light isoutcoupled at a different angle. Since volume phase gratings may exhibitnarrow angular properties, different gratings in the stack may be usedfor different angles. Light may be outcoupled at different locations atthe stack 1087, as exemplified in the drawing by a first outcoupled cone1088 a and a second outcoupled cone 1088 b originating from differentlocations in stack 1087.

FIG. 16 illustrates a side view of a waveguide 1010, wherein acholesteric liquid crystal grating (CLCG) 1070 is used for outcouplinglight out of waveguide 1010. A CLCG 1070 can be formed using cholestericliquid crystal that diffracts polarized light.

In some implementations, the CLCG 1070 diffracts circularly polarizedlight and the SLM 1018 (e.g., a liquid crystal spatial light modulatorarray) operates on linear polarized light. In such implementations,retarders may be employed to convert the circular polarized light intolinear polarized light and vice versa. A first quarter-wave retarder1072 may, for example, be disposed between waveguide 1010 and the SLM1018, and a second quarter-wave retarder 1074 may be disposed on theopposite side of the waveguide 1010. In some embodiments, light may beoutcoupled by the CLCG 1070 from the waveguide 1010 in the direction ofthe SLM 1018 with circular (e.g. right-hand circular) polarization. Thefirst quarter-wave retarder 1072 may rotate the polarization to linear(e.g. linear vertical) polarization. Accordingly, in some embodimentswhere the SLM 1018 operates on linearly polarized light (such as aliquid crystal spatial light modulator), use of the CLCG 1070 and thefirst quarter wave retarder 1072 may reduce the need for a linearpolarizer, as linear polarized light is output from the first quarterwave retarder 1072. Upon being reflected and imparted with modulation bythe SLM 1018, the linear polarized light passes again through the firstquarter-wave retarder 1072, again assuming circular (e.g. left handcircular) polarization. Upon passing through second quarter-waveretarder 1074, the circular polarized light may be converted back tolinear (e.g. linear horizontal) polarization. Other configurations arepossible.

As discussed above with regard to FIG. 15A and the outcoupling opticalelements 1014 including volume phase gratings, the CLCG 1070 may have agradient in coupling efficiency and/or pitch. The CLCG 1070 may, forexample, be configured to have a high diffractive efficiency furtheraway from the light source 1002, and a lower diffractive efficiencycloser to the light source 1002. As discussed, the amount of lightwithin the waveguide 1010 may decrease with increasing distance from thelight source 1002. By appropriately choosing the coupling efficiencyprofile of the CLCG 1070 along its length, the effect of decreasinglight within the waveguide 1010 may be at least partially compensated byan increase in the outcoupling efficiency of the CLCG 1070. This mayallow for a more homogenous intensity of outcoupled light across thelength of the waveguide 1010. Similarly, the pitch may be varied asdiscussed with regard to FIG. 15A. The pitch may, for example, be madesmall closer to the light source 1002 and larger farther from the lightsource 1002. Other configurations are possible.

Additionally, since the CLCG 1070 may exhibit narrow spectral andangular properties, one or more volume phase gratings or stack of volumephase gratings may be used in various embodiments. For example, asillustrated in FIG. 15B, the waveguide-based light distribution devicecan include a stack 1087 of cholesteric liquid crystal diffractiveelements for coupling light out of the waveguide 1010. The stack 1087may include various cholesteric liquid diffractive elements associatedwith different wavelength. Moreover, the stack 1087 may include variouscholesteric liquid crystal diffractive elements configured to diffractlight having different colors. For example, the stack 1087 may includemultiple (e.g. three) volume phase gratings, different gratingsassociated with wavelengths corresponding to different colors,respectively (e.g., red, green and blue). The narrow or modest bandwidthenables light to be outcoupled with the same angle for different colorsas individual color layers can be designed for each color.

The different variations described above can be used with any of theother devices, systems, configurations, method, and approaches discussedabove. Still other variations are possible.

For example, efficient coupling of a source like an LED with a narrowangle cone of emission may involve some volume to fit optics for beamshaping. FIG. 17A illustrates a design with source illumination that isdistributed across a SLM array such that coupling optics can be moreefficient and compact as the coupling optics need to shape the beam tocover a SLM array area rather than a narrow angle cone. In someembodiments, as illustrate in FIG. 17B, light is coupled out from thewaveguide 1010 when it interacts with the outcoupling optical element1014 rather than propagating via total internal reflection in thewaveguide 1010. Either volume phase grating or cholesteric liquidcrystal gratings can be used. In some embodiments, both volume phasegrating and cholesteric liquid crystal gratings can exhibit 100%efficiency.

In some embodiments, as illustrated in FIG. 18, a wedge-shaped waveguide1010 may be employed. The waveguide 1010 has an inclined or curvedsurface that produces a taper of the waveguide 1010. Consequently, oneend of the waveguide 1010 is thicker than another end. In theimplementation shown in FIG. 18, the light source 1002 is at the thickerend and couples light into this thicker end. When the waveguide 1010 hasa wedge shape (or a curved shape), the beam propagation angle can changeas the light propagates in the waveguide. This change in propagationangle is cause by reflections off the inclined surface. Accordingly, thepropagation angle can be tailored.

As discussed above, since both volume phase gratings and cholestericliquid crystal grating can have narrow (or modest) angular responses(e.g., high efficiency within ±2° or ±10°, respectively), light withinthese ranges is extracted by the outcoupling optical element 1014. Lightpropagating within this angular range within a planar waveguide may bedepleted as light outcoupled from the planar waveguide. However, aslight propagates through the wedge-shaped or tapered (e.g., curved)waveguide, the propagation angle of the light beam progressivelychanges. As a result, the angle of light can change as it propagateuntil the angle reaches the suitable angle for outcoupling by theoutcoupling optical element 1014. Light outcoupled from the wedge shapedor tapered waveguide 1010 can be more evenly distributed. This approachworks when for light sources that have a large angle cone for output.

EXAMPLES

1. A display device comprising:

one or more light emitters configured to emit light;

a first waveguide disposed with respect to said one or more lightemitters to receive light from said one or more light emitters, saidfirst waveguide configured to (i) eject light out of said waveguidehaving a first color along a first path, and (ii) eject light out ofsaid first waveguide having a second color along a second path; and

a spatial light modulator disposed with respect to said first waveguideto receive said light ejected from said waveguide and modulate saidlight,

wherein said one or more light emitters is configured to emit lighthaving a spectral distribution that includes spectral componentscorresponding to said first and second colors, and

wherein said display device is configured such that said light from saidfirst waveguide of said first color and said second color after beingmodulated by said spatial light modulator is directed along saidrespective first and second paths at different angles and is incident onrespective first and second spatial locations a distance from said firstwaveguide and spatial light modulator.

2. The display device of Example 1, wherein one or more light emitterscomprise one or more light emitting diodes (LEDs).

3. The display device of Example 2, wherein one or more light emitterscomprise one or more white light emitting diodes (WLEDs).

4. The display device of any of Examples 1-3, wherein said firstwaveguide is configured to (iii) eject light out of said first waveguidehaving a third color along a third path.

5. The display device of Example 4, wherein said spatial light modulatoris disposed with respect to said first waveguide to receive said lightof said third color ejected from said first waveguide and modulate saidlight, and said first waveguide is configured to direct said light afterbeing modulated by said spatial light modulator along said third path soas to be is incident on a third spatial location different from saidfirst and second spatial locations at a distance from said firstwaveguide and spatial light modulator.

6. The display device of any of Examples 1-5, further comprising:

a second waveguide having associated therewith an in-coupling opticalelement disposed with respect to said first waveguide and said firstpath to receive light from said first waveguide after being modulated bysaid spatial light modulator; and

a third waveguide having associated therewith an in-coupling opticalelement disposed with respect to said first waveguide and said secondpath to receive light from said first waveguide after being modulated bysaid spatial light modulator,

wherein said in-coming optical elements associated with said second andthird waveguides, respectively, are located at said first and secondspatial locations along said first and second paths, respectively, toreceive said light of said first and second colors, respectively.

7. The display device of Example 6, wherein said in-coupling opticalelements associated with said second and third waveguides are configuredto turn light into said second and third waveguides, respectively, suchthat said light is guided within said waveguides by total internalreflection.

8. The display device of Example 6 or 7, wherein said in-couplingoptical elements for said second and third waveguides comprise turningfeatures configured to redirect light into said second and thirdwaveguides, respectively, to be guided therein by total internalreflection.

9. The display device of any of Examples 6-8, wherein said in-couplingoptical elements comprise one or more diffractive optical elements,diffraction gratings, holographic optical elements, or metasurfaces.

10. The display device of any one of Examples 6-9, wherein one or moreof said in-coupling optical elements comprise a wavelength selectiveoptical element.

11. The display device of any of Examples 6-10, further comprising:

a fourth waveguide having associated therewith an in-coupling opticalelement disposed with respect to said first waveguide;

wherein said first waveguide is configured to (iii) eject light out ofsaid first waveguide having a third color along a third path,

wherein said spatial light modulator is disposed with respect to saidfirst waveguide to receive said light of said third color ejected fromsaid first waveguide and modulate said light, and said first waveguideis configured to direct said light of said third color after beingmodulated by said spatial light modulator along a third path so as to beincident on a third spatial location different from said first andsecond spatial locations at a distance from said first waveguide andspatial light modulator, and

wherein said in-coming optical elements associated with said fourthrespectively, is located at said third spatial locations along saidthird path to receive said light of said third color.

12. The display device of Example 11, wherein said in-coupling opticalelement associated with said fourth waveguide is configured to turnlight into said fourth waveguide, such that said light is guided withinsaid waveguide by total internal reflection.

13. The display device of Example 11 or 12, wherein said in-couplingoptical element for said fourth waveguide comprises turning featuresconfigured to redirect light into said fourth waveguide to be guidedtherein by total internal reflection.

14. The display device of any of Examples 11-13, wherein saidin-coupling optical element comprises one or more diffractive opticalelements, diffraction gratings, holographic optical elements, ormetasurfaces.

15. The display device of any one of Examples 11-14, wherein saidin-coupling optical element associated with said fourth waveguidecomprise a wavelength selective optical element.

16. The display device of any of the above examples, wherein saidwaveguide includes one or more turning elements configured to turn lightguided within said waveguide by total internal reflection out of saidwaveguide.

17. The display device of Example 16, wherein said one or more turningelements comprise turning features configured to redirect light guidedwithin said waveguide by total internal reflection out of saidwaveguide.

18. The display device of Example 16 or 17, wherein said one or moreturning elements comprise one or more diffractive optical elements,diffraction gratings, holographic optical elements, or metasurfaces.

19. The display device of any one of Examples 16-18, wherein said one ormore turning elements have wavelength dispersion.

20. The display device of any one of Examples 16-19, wherein said one ormore turning elements comprise a wavelength selective optical element.

21. A display device comprising:

one or more light emitters configured to emit light;

a first waveguide disposed with respect to said one or more lightemitters to receive light from said one or more light emitters such thatsaid light is guided therein by total internal reflection, said firstwaveguide configured to eject light guided within said first waveguideout of said waveguide;

a shutter system comprising a first shutter and a second shutter andcorresponding first and second color filters configured to selectivelytransmit first and second color light, respectively, said shutter systemdisposed with respect to said first waveguide to receive said lightejected from said waveguide such that light of said first and secondcolors from said first waveguide passes through said respective firstand second color filters, respectively, as well as through saidrespective first shutter and second shutters along respective first andsecond optical paths to respective first and second spatial location ata distance from said first waveguide;

a spatial light modulator disposed with respect to said first waveguideto receive said light ejected from said waveguide and modulate saidlight, said shutter system disposed with respect to said spatial lightmodulator such that said modulated light is directed along said firstand second optical paths to said respective first and second spatiallocation at a distance from said spatial light modulator; and

electronics in communication with said shutter system and said spatiallight modulator to (i) open said shutter associated with said firstcolor at a first time and close said shutter associated with said secondcolor when said spatial light modulator is configured to present animage corresponding to said first color and (ii) to open said shutterassociated with said second color and close said shutter associated withsaid first color at a second time when said spatial light modulator isconfigured to present an image corresponding to said second color,

wherein said one or more light emitters is configured to emit lighthaving a spectral distribution that includes spectral componentscorresponding to said first and second colors.

22. The display device of Example 21, wherein one or more light emitterscomprise one or more light emitting diodes (LEDs).

23. The display device of Example 22, wherein one or more light emitterscomprise one or more white light emitting diodes (WLEDs).

24. The display device of any of Examples 21-23, wherein said shuttersystem includes a third shutter and a corresponding third color filterconfigured to selectively transmit a third color light, said shuttersystem disposed with respect to said first waveguide to receive saidlight ejected from said waveguide such that light of said third colorfrom said first waveguide is selectively transmitted through said thirdcolor filter as well as through said third shutter along a respectivethird optical path to a third spatial location different separate fromsaid first and second spatial locations at a distance from said firstwaveguide.

25. The display device of Example 24,

wherein said one or more light emitters is configured to emit lighthaving a spectral distribution that includes spectral componentscorresponding to said third color,

wherein said shutter system is disposed with respect to said spatiallight modulator such that said modulated light from said spatial lightmodulator is directed along said third optical path to said thirdspatial location at a distance from said spatial light modulator, and

wherein said electronics is configured to (iii) open said shutterassociated with said third color at a third time and close said shuttersassociated with said first and second colors when said spatial lightmodulator is configured to present an image corresponding to said thirdcolor.

26. The display device of any of Examples 21-25, wherein said shuttersare disposed along said optical path between said color filters and saidspatial locations.

27. The display device of any of Examples 21-26, wherein said colorfilters are disposed along said optical path between said shutters andsaid spatial locations.

28. The display device of any of Examples 21-25, further comprising:

a second waveguide having associated therewith an in-coupling opticalelement disposed with respect to said first waveguide and said firstpath to receive light from first waveguide after being modulated by saidspatial light modulator; and

a third waveguide having associated therewith an in-coupling opticalelement disposed with respect to said first waveguide and said secondpath to receive light from first waveguide after being modulated by saidspatial light modulator,

wherein said in-coming optical elements associated with said second andthird waveguides, respectively, are located at said first and secondspatial locations along said first and second paths respectively toreceive said light of said first and second colors, respectively.

29. The display device of Example 26, wherein said in-coupling opticalelements associated with said second and third waveguides are configuredto turn light into said second and third waveguides, respectively, suchthat said light is guided within said waveguides by total internalreflection.

30. The display device of Example 26 or 27, wherein said in-couplingoptical elements for said second and third waveguides comprise turningfeatures configured to redirect light into said second and thirdwaveguides, respectively, to be guided therein by total internalreflection.

31. The display device of any of Examples 26-28, wherein saidin-coupling optical elements comprise one or more diffractive opticalelements, diffraction gratings, holographic optical elements, ormetasurfaces.

32. The display device of any one of Examples 26-29, wherein one or moreof said in-coupling optical elements comprise a wavelength selectiveoptical element.

33. The display device of Example 25, further comprising:

a second waveguide having associated therewith an in-coupling opticalelement disposed with respect to said first waveguide and said firstpath to receive light from first waveguide after being modulated by saidspatial light modulator; and

a third waveguide having associated therewith an in-coupling opticalelement disposed with respect to said first waveguide and said secondpath to receive light from first waveguide after being modulated by saidspatial light modulator,

a fourth waveguide having associated therewith an in-coupling opticalelement disposed with respect to said first waveguide and said thirdpath to receive light from first waveguide after being modulated by saidspatial light modulator.

34. The display device of Example 33, wherein said in-coupling opticalelements associated with said second, third, and fourth waveguides areconfigured to turn light into said second, third, and fourth waveguides,respectively, such that said light is guided within said waveguides bytotal internal reflection.

35. The display device of Example 34 or 35, wherein said in-couplingoptical elements for said second, third, and fourth waveguides compriseturning features configured to redirect light into said second, third,and fourth waveguides, respectively, to be guided therein by totalinternal reflection.

36. The display device of any of Examples 33-35, wherein saidin-coupling optical elements comprise one or more diffractive opticalelements, diffraction gratings, holographic optical elements, ormetasurfaces.

37. The display device of any one of Examples 33-36, wherein one or moreof said in-coupling optical elements comprise a wavelength selectiveoptical element.

38. The display device of any of the above examples, wherein saidwaveguide includes one or more turning elements configured to turn lightguided within said waveguide by total internal reflection out of saidwaveguide.

39. The display device of Example 38, wherein said one or more turningelements comprise turning features configured to redirect light guidedwithin said waveguide by total internal reflection out of saidwaveguide.

40. The display device of Example 38 or 39, wherein said one or moreturning elements comprise one or more diffractive optical elements,diffraction gratings, holographic optical elements, or metasurfaces.

41. The display device of any one of Examples 38-40, wherein said one ormore turning elements comprise a wavelength selective optical element.

42. A display device comprising:

one or more light emitters configured to emit light;

a first waveguide disposed with respect to said one or more lightemitters to receive light from said one or more light emitters such thatsaid light is guided therein by total internal reflection, said firstwaveguide configured to eject light guided within said first waveguideout of said waveguide;

a first beamsplitter configured to selectively direct light of a firstspectral distribution and a first color light along a first directionand a second spectral distribution along a second direction, said firstbeamsplitter disposed with respect to said first waveguide to receivesaid light ejected from said waveguide such that light of said first andsecond spectral distributions from said first waveguide are incident onsaid first beamsplitter and said light having said first and secondspectral distributions are directed along respective first and secondoptical paths, said light of said first spectral distribution and firstcolor being directed to a respective first spatial location at adistance from said first waveguide; and

a spatial light modulator disposed with respect to said first waveguideto receive said light ejected from said waveguide and modulate saidlight, said first beamsplitter disposed with respect to said spatiallight modulator such that said modulated light is directed along saidfirst and second optical paths and said light of said first color isdirected to said first spatial location at a distance from said spatiallight modulator,

wherein said one or more light emitters is configured to emit lighthaving a spectral distribution that includes spectral componentscorresponding to said first and second spectral distribution directedalong said respective first and second optical paths.

43. The display device of Example 42, wherein one or more light emitterscomprise one or more light emitting diodes (LEDs).

44. The display device of Example 43, wherein one or more light emitterscomprise one or more white light emitting diodes (WLEDs).

45. The display device of any of Examples 42-44, further comprising areflector to direct said light of said second spectral distributionoutput by said first beamsplitter to a second spatial location at adistance from said spatial light modulator.

46. The display device of any of Examples 42-45, further comprising asecond beamsplitter configured to receive said light of said secondspectral distribution output by said first beamspitter and selectivelydirect light of a second color along a second direction and a light of athird color along a third direction, said second beamsplitter disposedwith respect to said first waveguide to receive said light ejected fromsaid waveguide such that light of said second and third colors from saidfirst waveguide is incident on said second beamsplitter and saidrespective second and third color light are directed along respectivesecond and third optical paths to respective second and third spatiallocations at a distance from said first waveguide.

47. The display device of Examples 46,

wherein said one or more light emitters is configured to emit lighthaving a spectral distribution that includes spectral componentscorresponding to said second and third colors,

wherein said second beamsplitter is disposed with respect to saidspatial light modulator such that said modulated light from said spatiallight modulator having second and third colors is directed along saidrespective second and third optical paths to said respective second andthird spatial locations at a distance from said spatial light modulator.

48. The display device of any of Examples 42-47, wherein said firstbeamsplitter is disposed along said optical path between said spatiallight modulator and said first spatial locations.

49. The display device of Examples 46 or 47, wherein said first andsecond beamsplitters are disposed along said optical paths between saidspatial light modulator and said first, second, and third spatiallocations.

50. The display device of any of Examples 46, 47, or 49, wherein saidfirst beamsplitter is disposed along an optical path between said secondbeamsplitter and said spatial light modulator.

51. The display device of any of Examples 46, 47, 49 or 50, wherein saidsecond beamsplitter is disposed along an optical path between said firstbeamsplitter and said second and third spatial locations.

52. The display device of any of Examples 42-51, further comprising:

a second waveguide having associated therewith an in-coupling opticalelement disposed with respect to said first waveguide and said firstpath to receive light from said first waveguide after being modulated bysaid spatial light modulator; and

a third waveguide having associated therewith an in-coupling opticalelement disposed with respect to said first waveguide and said secondpath to receive light from said first waveguide after being modulated bysaid spatial light modulator,

wherein said in-coming optical elements associated with said second andthird waveguides, respectively, are located at said first and secondspatial locations along said first and second paths, respectively, toreceive said light of first and second colors, respectively.

53. The display device of Example 52, wherein said in-coupling opticalelements associated with said second and third waveguides are configuredto turn light into said second and third waveguides, respectively, suchthat said light is guided within said waveguides by total internalreflection.

54. The display device of Example 52 or 53, wherein said in-couplingoptical elements for said second and third waveguides comprise turningfeatures configured to redirect light into said second and thirdwaveguides, respectively, to be guided therein by total internalreflection.

55. The display device of any of Examples 52-53, wherein saidin-coupling optical elements comprise one or more diffractive opticalelements, diffraction gratings, holographic optical elements, ormetasurfaces.

56. The display device of any one of Examples 52-55, wherein one or moreof said in-coupling optical elements comprise a wavelength selectiveoptical element.

57. The display device of Example 46, further comprising:

a second waveguide having associated therewith an in-coupling opticalelement disposed with respect to said first waveguide and said firstpath to receive light from said first waveguide after being modulated bysaid spatial light modulator; and

a third waveguide having associated therewith an in-coupling opticalelement disposed with respect to said first waveguide and said secondpath to receive light from said first waveguide after being modulated bysaid spatial light modulator,

a fourth waveguide having associated therewith an in-coupling opticalelement disposed with respect to said first waveguide and said thirdpath to receive light from said first waveguide after being modulated bysaid spatial light modulator.

58. The display device of Example 57, wherein said in-coupling opticalelements associated with said second, third, and fourth waveguides areconfigured to turn light into said second, third, and fourth waveguides,respectively, such that said light is guided within said waveguides bytotal internal reflection.

59. The display device of Example 57 or 58, wherein said in-couplingoptical elements for said second, third, and fourth waveguides compriseturning features configured to redirect light into said second, third,and fourth waveguides, respectively, to be guided therein by totalinternal reflection.

60. The display device of any of Examples 57-59, wherein saidin-coupling optical elements comprise one or more diffractive opticalelements, diffraction gratings, holographic optical elements, ormetasurfaces.

61. The display device of any one of Examples 57-60, wherein one or moreof said in-coupling optical elements comprise a wavelength selectiveoptical element.

62. The display device of any of the above examples, wherein saidwaveguide includes one or more turning elements configured to turn lightguided within said waveguide by total internal reflection out of saidwaveguide.

63. The display device of Example 62, wherein said one or more turningelements comprise turning features configured to redirect light guidedwithin said waveguide by total internal reflection out of saidwaveguide.

64. The display device of Example 62 or 63, wherein said one or moreturning elements comprise one or more diffractive optical elements,diffraction gratings, holographic optical elements, or metasurfaces.

65. The display device of any one of Examples 62-64, wherein said one ormore turning elements comprise a wavelength selective optical element.

FURTHER EXAMPLES

1. A display device for a head mounted display comprising:

-   -   a waveguide based image source comprising:        -   one or more light emitters configured to emit light;        -   one or more waveguides disposed with respect to said one or            more light emitters to receive light from said one or more            light emitters such that light is guided within said one or            more light guides via total internal reflection, said one or            more waveguides configured to eject light out of said            waveguides; and        -   a spatial light modulator disposed with respect to one or            more waveguides to receive said light ejected from said one            or more waveguides and modulate said light,    -   wherein said one or more light emitters are configured to emit        light having a spectral distribution that includes spectral        components corresponding to first and second colors, and    -   said waveguide based image source is configured such that said        light of said first and second colors after being modulated by        said spatial light modulator is directed along said respective        first and second paths and is incident on respective first and        second spatial locations a distance from said one or more        waveguides and said spatial light modulator, and    -   an eyepiece element comprising a waveguide based light        distribution system comprising:        -   a first waveguide having associated therewith an in-coupling            optical element disposed with respect to one or more first            waveguides and said first path to receive light from said            one or more waveguides after being modulated by said spatial            light modulator; and        -   a second waveguide having associated therewith an            in-coupling optical element disposed with respect to said            one or more waveguides and said second path to receive light            from said one or more waveguides after being modulated by            said spatial light modulator,    -   wherein said in-coming optical elements associated with said        first and second waveguides, respectively, are located at said        first and second spatial locations along said first and second        paths respectively to receive said light of said first and        second colors, respectively.

42. The display system of Example 1, wherein one or more light emitterscomprise one or more light emitting diodes (LEDs).

43. The display system of Example 2, wherein one or more light emitterscomprise one or more white light emitting diodes (WLEDs).

44. The display system of any of Examples 1-3, wherein said waveguidebased image source is configured to output light of a third color alonga third path.

45. The display system of any of Examples 1-3, wherein said one or morelight emitters are configured to emit light having a spectraldistribution that includes spectral components corresponding to thirdcolor.

46. The display system of Example 5, wherein, said waveguide based imagesource is configured such that said light from of said third color afterbeing modulated by said spatial light modulator is directed along arespective a third path different from said first and second paths suchthat said first, second, and third color light are incident onrespective first second, and third spatial locations a distance fromsaid one or more waveguides and spatial light modulator.

47. The display system of any of example 6, wherein said waveguide basedlight distribution system comprises a third waveguide having associatedtherewith one or more in-coupling optical elements disposed with respectto said one or more waveguides in said waveguide based image source andsaid third path to receive light from said one or more waveguides afterbeing modulated by said spatial light modulator, said in-coming opticalelement associated with said third waveguide being located at said thirdspatial locations along said third path to receive said light of saidthird color light.

48. The display system of Example 7, wherein said in-coupling opticalelements associated with said third waveguides are configured to turnlight into said third waveguide, such that said light is guided withinsaid third waveguide by total internal reflection.

49. The display system of Example 7 or 8, wherein said in-couplingoptical elements for said third waveguide comprise turning featuresconfigured to redirect light into said third waveguide to be guidedtherein by total internal reflection.

50. The display system of any of the above examples, wherein saidin-coupling optical elements associated with said first and secondwaveguides are configured to turn light into said first and secondwaveguides, respectively, such that said light is guided within saidfirst and second waveguides by total internal reflection.

51. The display system of any of the above examples, wherein saidin-coupling optical elements for said first and second waveguidescomprise turning features configured to redirect light into said firstand second waveguides, respectively, to be guided therein by totalinternal reflection.

52. The display system of any of the above examples, wherein saidin-coupling optical elements comprise one or more diffractive opticalelements, diffraction gratings, holographic optical elements, ormetasurfaces.

53. The display system of any of the above examples, wherein one or moreof said in-coupling optical elements comprise a wavelength selectiveoptical element.

54. The display system of any of the above examples, wherein said one ormore waveguides include one or more turning elements configured to turnlight guided within said waveguide by total internal reflection out ofsaid waveguide.

55. The display system of Example 14, wherein said one or more turningelements comprise turning features configured to redirect light guidedwithin said waveguide by total internal reflection out of saidwaveguide.

56. The display system of Example 14 or 15, wherein said one or moreturning elements comprise one or more diffractive optical elements,diffraction gratings, holographic optical elements, or metasurfaces.

57. The display system of any one of Examples 14-16, wherein said one ormore turning elements comprise a wavelength selective optical element.

58. The display system of any of the above examples, wherein saidwaveguide based light distribution system comprise an exit pupilexpander.

59. The display system of any of the above examples, wherein said a headmounted display comprises an augmented reality head mounted displaysystem, said first and second waveguides in said eyepiece element beingtransparent.

ADDITIONAL EXAMPLES

1. A display device comprising:

a light source;

a waveguide disposed with respect to said light to receive light fromsaid light source, said waveguide including an outcoupling opticalelement configured to eject light out of said waveguide; and

a spatial light modulator disposed with respect to said waveguide toreceive said light ejected from said waveguides and modulate said light,

wherein said outcoupling optical element comprises a volume phasegrating.

2. A display device comprising:

a light source having a first spectral distribution;

a waveguide disposed with respect to said light to receive light fromsaid light source, said waveguide including an outcoupling opticalelement configured to eject light out of said waveguide; and

a spatial light modulator disposed with respect to said waveguide toreceive said light ejected from said waveguides and modulate said light,

wherein said outcoupling optical element comprises a liquid crystal.

3. The display device of Example 2, wherein said outcoupling opticalelement comprises a cholesteric liquid crystal.

4. The display device of Example 2, wherein said outcoupling opticalelement comprises a liquid crystal grating.

5. The display device of Example 2, wherein said outcoupling opticalelement comprises a cholesteric liquid crystal grating.

6. The display device of any of the above Examples, wherein displaydevice is included in a augmented reality head mounted display toprovide image content.

7. The display device of any of the above Examples, wherein said lightfrom said modulator is directed to an eyepiece of an augmented realityhead mounted display.

FURTHER ADDITIONAL VARIATIONS ON EXAMPLES

The following examples can depend from any of the above examples in eachof the sections (e.g., Section 1, Section 2, Section 3).

1. The display device of any of the Examples above, wherein the one ormore light emitters comprise a point light source.

2. The display device of any of the Examples above, wherein the one ormore light emitters comprise a line light source.

3. The display device of Example 3, wherein the one or more lightemitters comprise a substantially linear arrangement of LEDs.

4. The display device of Example 3, wherein the substantially lineararrangement of LEDs is associated with a microlens array.

5. The display device of any of the Examples above, comprising a lightguide directing light into the first waveguide.

6. The display device according to Example 5, wherein the light guide isdisposed on a boundary of the first waveguide, and a reflective elementis disposed along one boundary of the light guide.

7. The display device of any of the Examples above, wherein light isoutcoupled from the first waveguide via a first outcoupling element.

8. The display device of Example 7, wherein the first outcouplingelement comprises a volume phase grating.

9. The display device of Example 7, wherein the first outcouplingelement comprises a cholesteric liquid crystal grating.

10. The display device of any of Example 7-9, wherein a diffractionefficiency of the first outcoupling element varies along a distance ofthe first outcoupling element to the one or more light emitters.

11. The display device of Example 10, wherein the diffraction efficiencydecreases monotonically with increasing distance from the one or morelight emitters.

12. The display device of any of Examples 7-11, wherein a pitch of thefirst outcoupling element varies along a distance of the firstoutcoupling element to the one or more light emitters.

13. The display device according to Examples 8-12, wherein the firstoutcoupling element comprises a stack of multiple layers.

14. The display device according to Example 13, wherein a first layerwithin the stack is configured to outcouple light of a first color fromthe first waveguide, and a second layer within the stack is configuredto outcouple light of a second color from the first waveguide.

15. The display device according to Example 13, wherein a first layerwithin the stack is configured to outcouple a first color, and a secondlayer within the stack is configured to outcouple the first color.

16. The display device according to Example 13, wherein a first layerwithin the stack is configured to outcouple light encountering aboundary of the first waveguide at a first angle, and a second layerwithin the stack is configured to outcouple light encountering aboundary of the first waveguide at a second angle.

17. The display device according to Example 9, wherein a firstquarter-wave retarder is disposed between the spatial light modulatorand the first waveguide.

18. The display device according to Example 17, wherein a secondquarter-wave retarder is disposed on a boundary of the waveguideopposite to the spatial light modulator.

19. The display device according to any of the Examples above, whereinthe light from the one or more light emitters is directed substantiallyoff an axis of the first waveguide.

20. The display device of Example 19, wherein the display device doesnot comprise focusing optics between the one or more light emitters andthe first waveguide.

21. The display device of any of the Examples above, wherein the firstwaveguide is substantially wedge-shaped.

22. The display device of Example 21, wherein the wedge-shaped firstwaveguide is configured to change the angle of light reflecting off aboundary of the first waveguide.

It is contemplated that the innovative aspects may be implemented in orassociated with a variety of applications and thus includes a wide rangeof variation. Variations, for example, in the shape, number, and/oroptical power of the EPE's are contemplated. The structures, devices andmethods described herein may particularly find use in displays such aswearable displays (e.g., head mounted displays) that can be used foraugmented and/or virtually reality. More generally, the describedembodiments may be implemented in any device, apparatus, or system thatcan be configured to display an image, whether in motion (such as video)or stationary (such as still images), and whether textual, graphical orpictorial. It is contemplated, however, that the described embodimentsmay be included in or associated with a variety of electronic devicessuch as, but not limited to: mobile telephones, multimedia Internetenabled cellular telephones, mobile television receivers, wirelessdevices, smartphones, Bluetooth® devices, personal data assistants(PDAs), wireless electronic mail receivers, hand-held or portablecomputers, netbooks, notebooks, smartbooks, tablets, printers, copiers,scanners, facsimile devices, global positioning system (GPS)receivers/navigators, cameras, digital media players (such as MP3players), camcorders, game consoles, wrist watches, clocks, calculators,television monitors, flat panel displays, electronic reading devices(e.g., e-readers), computer monitors, auto displays (including odometerand speedometer displays, etc.), cockpit controls and/or displays,camera view displays (such as the display of a rear view camera in avehicle), electronic photographs, electronic billboards or signs,projectors, architectural structures, microwaves, refrigerators, stereosystems, cassette recorders or players, DVD players, CD players, VCRs,radios, portable memory chips, washers, dryers, washer/dryers, parkingmeters, head mounted displays and a variety of imaging systems. Thus,the teachings are not intended to be limited to the embodiments depictedsolely in the Figures, but instead have wide applicability as will bereadily apparent to one having ordinary skill in the art.

Various modifications to the embodiments described in this disclosuremay be readily apparent to those skilled in the art, and the genericprinciples defined herein may be applied to other embodiments withoutdeparting from the spirit or scope of this disclosure. Thus, the claimsare not intended to be limited to the embodiments shown herein, but areto be accorded the widest scope consistent with this disclosure, theprinciples and the novel features disclosed herein. The word “exemplary”is used exclusively herein to mean “serving as an example, instance, orillustration.” Any embodiment described herein as “exemplary” is notnecessarily to be construed as preferred or advantageous over otherembodiments. Additionally, a person having ordinary skill in the artwill readily appreciate, the terms “upper” and “lower”, “above” and“below”, etc., are sometimes used for ease of describing the figures,and indicate relative positions corresponding to the orientation of thefigure on a properly oriented page, and may not reflect the properorientation of the structures described herein, as those structures areimplemented.

Certain features that are described in this specification in the contextof separate embodiments also can be implemented in combination in asingle embodiment. Conversely, various features that are described inthe context of a single embodiment also can be implemented in multipleembodiments separately or in any suitable subcombination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. Further, the drawings may schematically depict one more exampleprocesses in the form of a flow diagram. However, other operations thatare not depicted can be incorporated in the example processes that areschematically illustrated. For example, one or more additionaloperations can be performed before, after, simultaneously, or betweenany of the illustrated operations. In certain circumstances,multitasking and parallel processing may be advantageous. Moreover, theseparation of various system components in the embodiments describedabove should not be understood as requiring such separation in allembodiments, and it should be understood that the described programcomponents and systems can generally be integrated together in a singlesoftware product or packaged into multiple software products.Additionally, other embodiments are within the scope of the followingclaims. In some cases, the actions recited in the claims can beperformed in a different order and still achieve desirable results.

Various example embodiments of the invention are described herein.Reference is made to these examples in a non-limiting sense. They areprovided to illustrate more broadly applicable aspects of the invention.Various changes may be made to the invention described and equivalentsmay be substituted without departing from the true spirit and scope ofthe invention. In addition, many modifications may be made to adapt aparticular situation, material, composition of matter, process, processact(s) or step(s) to the objective(s), spirit or scope of the presentinvention. Further, as will be appreciated by those with skill in theart that each of the individual variations described and illustratedherein has discrete components and features which may be readilyseparated from or combined with the features of any of the other severalembodiments without departing from the scope or spirit of the presentinventions. All such modifications are intended to be within the scopeof claims associated with this disclosure.

The invention includes methods that may be performed using the subjectdevices. The methods may comprise the act of providing such a suitabledevice. Such provision may be performed by the end user. In other words,the “providing” act merely requires the end user obtain, access,approach, position, set-up, activate, power-up or otherwise act toprovide the requisite device in the subject method. Methods recitedherein may be carried out in any order of the recited events which islogically possible, as well as in the recited order of events.

Example aspects of the invention, together with details regardingmaterial selection and manufacture have been set forth above. As forother details of the present invention, these may be appreciated inconnection with the above-referenced patents and publications as well asgenerally known or appreciated by those with skill in the art. The samemay hold true with respect to method-based aspects of the invention interms of additional acts as commonly or logically employed.

In addition, though the invention has been described in reference toseveral examples optionally incorporating various features, theinvention is not to be limited to that which is described or indicatedas contemplated with respect to each variation of the invention. Variouschanges may be made to the invention described and equivalents (whetherrecited herein or not included for the sake of some brevity) may besubstituted without departing from the true spirit and scope of theinvention. In addition, where a range of values is provided, it isunderstood that every intervening value, between the upper and lowerlimit of that range and any other stated or intervening value in thatstated range, is encompassed within the invention.

Also, it is contemplated that any optional feature of the inventivevariations described may be set forth and claimed independently, or incombination with any one or more of the features described herein.Reference to a singular item, includes the possibility that there areplural of the same items present. More specifically, as used herein andin claims associated hereto, the singular forms “a,” “an,” “said,” and“the” include plural referents unless the specifically stated otherwise.In other words, use of the articles allow for “at least one” of thesubject item in the description above as well as claims associated withthis disclosure. It is further noted that such claims may be drafted toexclude any optional element. As such, this statement is intended toserve as antecedent basis for use of such exclusive terminology as“solely,” “only” and the like in connection with the recitation of claimelements, or use of a “negative” limitation.

Without the use of such exclusive terminology, the term “comprising” inclaims associated with this disclosure shall allow for the inclusion ofany additional element—irrespective of whether a given number ofelements are enumerated in such claims, or the addition of a featurecould be regarded as transforming the nature of an element set forth insuch claims. Except as specifically defined herein, all technical andscientific terms used herein are to be given as broad a commonlyunderstood meaning as possible while maintaining claim validity.

The breadth of the present invention is not to be limited to theexamples provided and/or the subject specification, but rather only bythe scope of claim language associated with this disclosure.

1. A display device comprising: a first light emitter having a firstspectral distribution; a first waveguide disposed with respect to saidfirst light emitter to receive light from said first light emitter, saidfirst waveguide configured to eject light out of said waveguide along afirst path; a second light emitter having a second spectral distributiondifferent from said first spectral distribution of said first lightemitter; a second waveguide disposed with respect to said second lightemitter to receive light from said second light emitter, said secondwaveguide configured to eject light out of said waveguide along a secondpath; and a spatial light modulator disposed with respect to said firstand second waveguides to receive said light ejected from said first andsecond waveguides and modulate said light, wherein said display deviceis configured such that said light from said first and second waveguidesafter being modulated by said spatial light modulator is directed alongsaid first and second paths at different angles such that said lightfrom said first waveguide and said light from said second waveguideafter being modulated by said spatial light modulator are incident onrespective first and second spatial locations a distance from saidwaveguides and spatial light modulator.
 2. The display device of claim1, wherein said first and second light emitters comprise light emittingdiodes (LEDs).
 3. The display device of claim 2, wherein said first andsecond light emitters comprise first and second color light emittingdiodes (LEDs), said first color LED having a different color than saidsecond LED.
 4. The display device of claim 1, wherein said first andsecond waveguides comprise planar waveguides and said first and secondemitters are disposed with respect to edges of said first and secondwaveguides to inject light into an edge of said first and secondwaveguides, respectively.
 5. The display device of claim 1, wherein saidfirst and second waveguides include turning features to eject light outof said first and second waveguide along first and second pathsrespectively.
 6. The display device of claim 5, wherein said turningfeatures form part of a diffractive optical element, a diffractiongrating, a holographic optical element, or metasurface.
 7. The displaydevice of claim 1, wherein the spatial light modulator comprises atransmissive spatial light modulator configured to modulate lighttransmitted through said spatial light modulator.
 8. The display deviceof claim 1, wherein the spatial light modulator comprises a reflectivespatial light modulator configured to reflect and modulate lightincident thereon.
 9. The display device of claim 1, further comprising:a third light emitter having a third spectral distribution differentfrom said first and second spectral distributions; and a third waveguidedisposed with respect to said third light emitter to receive light fromsaid third light emitter, said third waveguide configured to eject lightout of said waveguide along a third path, said spatial light modulatordisposed with respect to said third waveguide to receive said lightejected from said third waveguide and modulate said light, wherein saiddisplay device is configured such that said light from said thirdwaveguide after being modulated by said spatial light modulator isdirected along said third path at a different angle from said first andsecond path such that said light from said first, second, and thirdwaveguides after being modulated by said spatial light modulator areincident on respective first, second, and third spatial locations adistance from said waveguides and spatial light modulator.
 10. Thedisplay device of claim 9, wherein said first, second, and third lightemitters comprise light emitting diodes (LEDs).
 11. The display deviceof claim 10, wherein said first, second, and third light emitterscomprise first, second, and third color light emitting diodes (LEDs),said first color LED having a different color than said second color LEDand third color LED, and said second color LED having a different colorthan said third color LED.
 12. The display device of claim 11, whereinsaid first, second, and third light emitters comprise red, green, andblue light emitting diodes (LEDs), respectively.
 13. The display deviceof claim 9, wherein said first, second, and third waveguides compriseplanar waveguides and said first, second, and third light emitters aredisposed with respect to edges of said first, second, and thirdwaveguides to inject light into an edge of said first, second, and thirdwaveguides, respectively.
 14. The display device of claim 9, whereinsaid first, second and third waveguides include turning features toeject light out of said first, second and third waveguides along first,second, and third paths, respectively.
 15. The display device of claim14, wherein said turning features form part of a diffractive opticalelement, a diffraction grating, a holographic optical element, or ameta-surface.
 16. The display device of claim 9, wherein the spatiallight modulator comprises a transmissive spatial light modulatorconfigured to modulate light transmitted through said spatial lightmodulator.
 17. The display device of claim 9, wherein the spatial lightmodulator comprises a reflective spatial light modulator configured toreflect and modulate light incident thereon.
 18. The display device ofclaim 1, further comprising: a fourth waveguide having associatedtherewith an in-coupling optical element disposed with respect to saidfirst waveguide and said first path to receive light from firstwaveguide after being modulated by said spatial light modulator; and afifth waveguide having associated therewith an in-coupling opticalelement disposed with respect to said second waveguide and said secondpath to receive light from second waveguide after being modulated bysaid spatial light modulator, wherein said in-coming optical elementsassociated with said fourth and fifth waveguides, respectively, arelocated at said first and second spatial locations along said first andsecond paths, respectively, to receive said light from said first andsecond light emitters, respectively.
 19. The display device of claim 18,wherein said in-coupling optical elements associated with said fourthand fifth waveguides are configured to turn light into said fourth andfifth waveguides, respectively, such that said light is guided withinsaid waveguides by total internal reflection.
 20. The display device ofclaim 18, wherein said in-coupling optical elements for said fourth andfifth waveguides comprise turning features configured to redirect lightinto said fourth and fifth waveguides, respectively, to be guidedtherein by total internal reflection.
 21. The display device of claim20, wherein said in-coupling optical elements comprise one or morediffractive optical elements, diffraction gratings, holographic opticalelements, or metasurfaces.
 22. The display device of claim 18, whereinone or more of said in-coupling optical elements comprise a wavelengthselective optical elements.
 23. The display device of claim 18, furthercomprising a sixth waveguide.
 24. The display device of claim 23,further comprising: a third light emitter having a third spectraldistribution different from said first and second spectraldistributions; and a third waveguide disposed with respect to said thirdlight emitter to receive light from said third light emitter, said thirdwaveguide configured to eject light out of said waveguide along a thirdpath, said spatial light modulator disposed with respect to said thirdwaveguide to receive said light ejected from said third waveguide andmodulate said light, wherein said display device is configured such thatsaid light from said third waveguide after being modulated by saidspatial light modulator is directed along said third path at a differentangle from said first and second path such that said light from saidfirst, second, and third waveguides after being modulated by saidspatial light modulator are incident on respective first, second, andthird spatial locations a distance from said waveguides and spatiallight modulator.
 25. The display device of claim 24, wherein said sixthwaveguide has associated therewith an in-coupling optical elementdisposed with respect to said third waveguide and said third path toreceive light from third waveguide after being modulated by said spatiallight modulator.
 26. The display device of claim 25, wherein saidin-coming optical element associated with said sixth waveguide islocated at said third spatial location along said third path to receivesaid light from said third light emitter.
 27. The display device ofclaim 24, wherein said first, second, and third light emitters comprisefirst, second, and third color light emitting diodes (LEDs), said firstcolor LED having a different color than said second color LED and thirdcolor LED, and said second color LED having a different color than saidthird color LED.
 28. The display device of claim 27, wherein said first,second, and third light emitters comprise red, green, and blue lightemitting diodes (LEDs) respectively.
 29. The display device of claim 23,wherein said in-coupling optical element associated with said fifthwaveguide is wavelength selective and is configured to turn more lightof a first color into said fifth waveguide such that said first colorlight is guided within said fifth waveguide by total internal reflectionand is configured to turn more light of a second color into said sixthwaveguide such that said second color light is guided within said sixthwaveguide by total internal reflection.
 30. The display device of claims29, wherein said wavelength selective optical element associated withsaid fifth waveguide is configured to redirect light of said first colorinto said fifth waveguide by reflection such that said light of saidfirst color is guided within said fifth waveguide and light of saidsecond color is transmitted through said wavelength selective opticalelement and said fifth waveguide into said sixth waveguide and isredirected by said wavelength selective optical element such that lightof said second color is guided within said sixth waveguide.
 31. Thedisplay device of claim 29, wherein said wavelength selective opticalelement associated with said fifth waveguide comprises one or morediffractive optical elements, diffraction gratings, holographic opticalelements, or metasurfaces.
 32. The display device of claim 29, furthercomprising a third light emitter having a third spectral distribution,said third light emitter disposed with respect to said third waveguidesuch that said third waveguide receives light from said third lightemitter and said third waveguide ejects said light out of said waveguidealong said third path and is incident on said second spatial location adistance from said waveguides and spatial light modulator.
 33. Thedisplay device of claim 1, wherein the first light emitter comprises apoint light source.
 34. The display device of claim 1, wherein the firstlight emitter comprises a line light source.
 35. The display device ofclaim 34, wherein the first light emitter comprises a substantiallylinear arrangement of LEDs.
 36. The display device of claim 35, whereinthe substantially linear arrangement of LEDs is associated with amicrolens array.
 37. The display device of claim 1, comprising a lightguide directing light into the first waveguide.
 38. The display deviceaccording to claim 37, wherein the light guide is disposed on a boundaryof the first waveguide, and a reflective element is disposed along oneboundary of the light guide.
 39. The display device of claim 1, whereinlight is outcoupled from the first waveguide via a first outcouplingelement.
 40. The display device of claim 39, wherein the firstoutcoupling element comprises a volume phase grating.
 41. The displaydevice of claim 39, wherein the first outcoupling element comprises acholesteric liquid crystal grating.
 42. The display device of claim 39,wherein a diffraction efficiency of the first outcoupling element variesalong a distance of the first outcoupling element to the first lightemitter.
 43. The display device of claim 42, wherein the diffractionefficiency decreases monotonically with increasing distance from thefirst light emitter.
 44. The display device of claim 39, wherein a pitchof the first outcoupling element varies along a distance of the firstoutcoupling element to the first light emitter.
 45. The display deviceaccording to claim 39, wherein the first outcoupling element comprises astack of multiple layers.
 46. The display device according to claim 45,wherein a first layer within the stack is configured to outcouple lightof a first color from the first waveguide, and a second layer within thestack is configured to outcouple light of a second color from the firstwaveguide.
 47. The display device according to claim 45, wherein a firstlayer within the stack is configured to outcouple a first color, and asecond layer within the stack is configured to outcouple the firstcolor.
 48. The display device according to claim 45, wherein a firstlayer within the stack is configured to outcouple light encountering aboundary of the first waveguide at a first angle, and a second layerwithin the stack is configured to outcouple light encountering aboundary of the first waveguide at a second angle.
 49. The displaydevice according to claim 39, wherein a first quarter-wave retarder isdisposed between the spatial light modulator and the first waveguide.50. The display device according to claim 49, wherein a secondquarter-wave retarder is disposed on a boundary of the waveguideopposite to the spatial light modulator.
 51. The display deviceaccording to claim 1, wherein the light from the first light emitter isdirected substantially off an axis of the first waveguide.
 52. Thedisplay device of claim 1, wherein the display device does not comprisefocusing optics between the first light emitter and the first waveguide.53. The display device of claim 1, wherein the first waveguide issubstantially wedge-shaped.
 54. The display device of claim 53, whereinthe wedge-shaped first waveguide is configured to change the angle oflight reflecting off a boundary of the first waveguide.